case study 2 draganski et al. (2006)

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Temporal and spatial dynamics of brain structure changes during extensive learning

Affiliation.

1 Department of Neurology, University of Regensburg, 93053 Regensburg, Germany.
PMID: 16763039
PMCID: PMC6675198
DOI: 10.1523/JNEUROSCI.4628-05.2006

The current view regarding human long-term memory as an active process of encoding and retrieval includes a highly specific learning-induced functional plasticity in a network of multiple memory systems. Voxel-based morphometry was used to detect possible structural brain changes associated with learning. Magnetic resonance images were obtained at three different time points while medical students learned for their medical examination. During the learning period, the gray matter increased significantly in the posterior and lateral parietal cortex bilaterally. These structural changes did not change significantly toward the third scan during the semester break 3 months after the exam. The posterior hippocampus showed a different pattern over time: the initial increase in gray matter during the learning period was even more pronounced toward the third time point. These results indicate that the acquisition of a great amount of highly abstract information may be related to a particular pattern of structural gray matter changes in particular brain areas.

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Gray matter increase related to…

Gray matter increase related to learning. Statistical parametric maps demonstrating the structural difference…

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Chapter 4: Biological Approaches to Understanding Behaviour

Chapter outline, 1. the rise of the biological approach in psychology, 2. research methods of the biological approach.

2.1 Correlational Studies

2.2 Case Studies

2.3 experiments, 2.4 ethics and research methods of the biological approach, 3. the brain and behaviour, 3.1 techniques used to study the brain in relation to behaviour, 3.2 localisation, 3.3 neuroplasticity, 3.4 neurotransmitters and their effect on behaviour, 3.5 assessment advice, 4. hormones, pheromones and behaviour, 4.1 hormones and their effect on behaviour.

4.2 Pheromones and Their Effect on Behaviour

4.3 Assessment Advice

5. genetics and behaviour, 5.1 genes and behaviour, 5.2 genetic similarities, 5.3 evolutionary explanations for behaviour, 5.4 assessment advice, 6. the role of animal research in understanding human behaviour, 6.1 can animal research provide an insight into human behaviour.

6.2 The Value of Animal Models in Research into the Brain and Behaviour

6.3 The Value of Animal Models in Research into Hormones and/or Pheromones

6.4 The Value of Animal Models in Research into Genetics and Behaviour

6.5 Ethical Considerations in Animal Research

6.6 Assessment Advice

Essential Questions What research methods do psychologists adopting a biological approach use to study behaviour? What techniques do they use to study the brain? How do the brain’s neural networks change over time and in response to learning and the environment? How do neurotransmitters affect behaviour? How do hormones and pheromones influence behaviour? How do genes influence behaviour? How does evolutionary psychology explain behaviour? What is the role of animal research in understanding human behaviour?

Myths and Misconceptions

Psychological research 'proves' hypotheses.

Never use the word 'prove' or 'proven' in your writing. Psychological research tests hypotheses and explains behaviour. Use 'supported', 'demonstrated that', but nothing is ever 'proved' or 'proven.'

The brain is far too complex to be studied in a meaningful way.

Innovative research in both the medical and biological psychology fields has made immense progress in revealing how the brain works and how it affects behaviour. In particular, technological advances in being able to generate images of the brain have enabled scientific research in this area to progress at a rapid pace. Have a look at the research being carried out at King’s College London into infant brain development or at the Human Genome Project.

One day, it will be possible to use genetics to explain a substantial amount of human behaviour.

Although a considerable amount of research into genetically inherited behaviour has been conducted, scientists are still unable to state with certainty the degree to which behaviours such as aggression or disorders such as major depressive disorder are predominantly influenced by genes. Indeed, as human behaviour is so complex, working out which genes are responsible for different behaviours is a phenomenally difficult undertaking for scientists. Moreover, determining how far genes influence behaviour is further complicated by the influence of external environmental factors such as stress and type of upbringing on both our behaviour and our genetic makeup.

Pheromones can influence our behaviour without our awareness.

Some researchers have claimed that pheromones secreted from our body can influence the behaviour of others. The perfume industry promotes this idea, which is strange as pheromones are odourless! However, many researchers have questioned the existence of human pheromones in humans and argue that pheromone research in humans is based on flawed assumptions. The evolutionary biologist Tristram Wyatt had written extensively about this, and his TED talk on the subject is very interesting.

During the 19th century, a quiet revolution in assessing how brain and behaviour are linked was taking place in the consulting clinics of such physicians as Paul Broca in France and Carl Wernicke in Germany. By adopting a systematic analysis of patients with language difficulties, these researchers helped to establish the scientific study of brain localization. Broca’s analysis of speech production deficits in his patients along with post-mortem brain analysis of some of these patients helped him to isolate a left frontal brain area that is responsible for the generation of language.

Today, this area is known as Broca’s area. Taking the same approach, Wernicke demonstrated that an area of the temporal lobe called the posterior superior temporal gyrus caused deficits in speech comprehension and the ability to produce meaningful language. This area is now known as Wernicke’s area. The work conducted by Wernicke and Broca and other researchers at the time led to the acknowledgement of the importance of studying brain-damaged individuals. This has resulted in the case study approach becoming a significant research tool in modern biological psychology and has led to the establishment of a discipline in psychology called clinical neuropsychology.

Researchers like Broca and Wernicke were at the forefront of the 19th-century movement towards a more systematic, scientific way of investigating the natural world. One of the most famous proponents of this approach was Charles Darwin, who, in producing his theory of evolution, had himself documented thousands of observations around the world to provide evidence for his theory. At that stage, science was a long way from understanding evolutionary mechanisms down to the genetic level as a result of the lack of scientific technology. However, scientific advances in research and technology eventually revealed that genes formed the building blocks of evolutionary mechanisms. In the last couple of decades, the role that genes play in behaviour has led to the establishment of evolutionary psychology and also research into how far behaviour such as intelligence may be inherited.

Significant advances in brain imaging technology have helped to propel the legacy of researchers like Broca and Wernicke even further forwards with the use in the modern psychology of techniques that can image the live brain. Not only have such technologies reinforced findings from neuropsychological research into localization they have also enabled researchers to assess cognitive processes such as memory and thinking in individuals without brain damage. Consequently, such research has enabled researchers to make significant advances in understanding the brain and behaviour relationship.

Furthermore, in conjunction with the medical field and also advances in medical science, biological psychologists have also increased our understanding of how hormones and pheromones affect behaviour.

Researchers who take a biological approach to understanding behaviour believe that all human behaviour has a biological basis. This is not to say they believe that it is only biological, but that there is a relationship between the human body and especially the brain (the structure and processes of the human nervous system) and human behaviour. Moreover, because the nervous systems of many animals are similar in their structure and processes to that of humans, biological psychologists use animals in research to gain understanding about human behaviour.

The most common research methods used in the biological approach are:

Correlational studies

Case studies

Experiments

Ask Yourself What difficulties do you think psychologists face when studying the brain?

2.1 Correlation Studies

Correlational research measures the relationship between two variable that are themselves not manipulated. Correlational studies in the biological approach focus on finding a relationship between a behaviour and inherited traits. This relationship is called the amount of heritability that a behaviour has. Correlational studies will usually be twin studies and adoption studies, which are important sources of information about the link between genetics and behaviour. Such studies are useful because they can suggest how much different behaviours are the result of genes and how much is down to environmental influences. The likelihood of twins or siblings sharing a genetic trait is measured by the concordance rate, which is expressed as a decimal or a percentage. So if one of two identical twins has depression, the likelihood of the other twin also suffering depression can be expressed as a decimal from 0 to 1, with 1 being perfect certainty that the other will have it, or as a percentage chance of 0-100%. A concordance rate of 0.7 is considered very high for many behaviours. This means that there is a 70% chance of the other twin having depression.

Apart from twin and adoption research, in biological psychology correlational studies are also used to show relationships between behaviours and activity in certain brain areas.

Focus on Research – a twin study (correlational study)

Later in the course, you will look at explanations for major depressive disorder (MDD). One of the biological explanations is that MDD is at least partially genetic, and therefore is inherited. To test the heritability of MDD, Kendler et al. (2006) conducted a huge study in Sweden, with personal interviews of 42,161 twins, including 15,493 complete pairs, from the national Swedish Twin Registry. The researchers estimated the heritability of MDD at 35-40%, with heritability being significantly higher in women than men (42% to 29%).

They found that twin pair resemblance for lifetime MDD was not predicted by the number of years the twins had lived together in the home of origin or by the frequency of current contact. This tends to support the idea of a biological, rather than a sociocultural (environmental) explanation for MDD.

A case study involves the in-depth and detailed study of an individual or a particular group in order to obtain a deep understanding of behaviour. In the biological approach, this method is particularly favoured in the field of neuropsychology in order to establish a relationship between the brain and a specific behaviour. For example, a psychologist studying the biological foundation of amnesia would analyse the behaviour of a patient and correlate any deficits in memory with a detailed biological analysis obtained through brain imaging. Such research can help inform existing biological theories of memory and indeed could lead to the development of new theories. Case studies can go on for many years (longitudinal case studies) and often have within them several different methods, such as observations, use of brain imaging techniques and interviews.

Focus on Research – a case study – H.M.

One of the most famous amnesiac patients in the history of psychology was Henry Molaison and a detailed outline of his case study and subsequent legacy is provided by Squire (2009). You will see him referred to as H.M. in many books and articles and this is due to the requirement of participant confidentiality. However, very rarely, some research participants and/or their partners/family are happy for the full name to be known and one example is the case study of Clive Wearing in Chapter 5.

Born in 1926, Henry Molaison had been hit by a cyclist when he was seven and from the age of ten then started to have epileptic seizures that subsequently started to worsen as he neared adulthood. By the time he was twenty-seven, these seizures were so crippling that he underwent surgery for a bilateral medial temporal lobe resection. This involved cutting out significant portions of Henry’s brain in the temporal lobe area to try to control the seizures. However, the surgery resulted in severe anterograde amnesia, a type of amnesia that leads to deficits in encoding new information into the brain. It should be noted that when Henry had this operation, knowledge about the brain’s functions was limited hence the dramatic consequences of such an operation were little understood at the time.

Henry’s legacy in terms of our knowledge about memory is highly significant because as a result of extensive research with him up to his death in 2008, Henry had contributed a wealth of data about his memory function. Firstly, given that his short-term memory was normal, this demonstrated that the short- and long-term memory systems in the brain must, to some extent, be separate otherwise Henry’s brain damage would also have affected short-term memory processing. This finding reinforced the ‘separate stores’ claims of the multi-store model of memory that you will study in Chapter 5.

However, what was intriguing about Henry’s case, and indeed other similar cases of anterograde amnesia, is that it demonstrated that there are different types of long-term memory. Henry’s brain damage specifically targeted episodic memory and he was, therefore, unable to form new memories of any event experienced after the surgery and this continued to the end of his life. However, he was able to form new procedural longterm memories. Procedural memories are those memories which are automatic such as knowing how to drive. This type of knowledge does not start out as automatic because clearly skills such as driving must be learned. These skills develop over time, however, and activities such as driving become easier and more automatic if we practise them regularly.

Despite his extensive brain damage, Henry could form new procedural memories on activities such as a pursuit rotor task in which a participant tracks a moving object on a screen with a cursor. This task requires precision and must be practised regularly to gain expertise in the task. Henry was able to show that he could develop these skills even though he could not remember previous practice sessions due to his episodic memory deficit. Such testing with Henry and other amnesic patients led memory researchers to understand more about how memory processing is carried out in the brain and in particular to understand that skill memory does not require the use of medial temporal lobe systems to work effectively.

You can use this case study of Henry Molaison as a key study in both the brain imaging techniques and the localization of function section later in this chapter.

Experiments are used to measure the effect of an independent variable (IV) on a dependent variable (DV). They can be conducted under either artificial or natural conditions. In a true experiment, which tries to determine a cause and effect relationship between the IV and the DV, the IV is manipulated, the DV is measured and all extraneous variables that might affect the outcome of the experiment are carefully controlled, often by conducting such an experiment in a laboratory. The participants are randomly allocated to groups and the relationship found between the IV and the DV is a cause and effect relationship.

Quasi-experiments are experiments where the participants are allocated to groups by precharacteristics, such as day-shift or night-shift, class in school, ability in maths, gender, ethnicity, age, etc. There is sometimes, but not always a manipulated IV and control of other variables, but because of the non-equivalent groups, the relationship that is found is correlational. Quasi experiments and true experiments are common methods in biological psychology. Maguire’s study that you will read about later in this chapter is an example of a quasi-experiment that did not have a manipulated IV.

Experiments often involve non-human animals because they are extremely difficult to study in their natural habitat. As, unlike humans, animals do not guess the purpose of the experiment, results gained from animal research are free of participant expectations. Nevertheless, many people would argue that experimenting on animals is also unethical, which will be discussed later.

Focus on Research – experiment – Antonova et al. (2011)

Antonova et al. (2011) followed up on results from animal research that showed that a neurotransmitter called acetylcholine (ACh) acted in the brain to aid spatial memory, and that this action could be reduced or prevented by the chemical scopolamine. They tested twenty men with an average age of 28 years in a virtual reality maze. Everyone was randomly allocated to either a scopolamine injection group or a saline injection group (placebo/control group). Then their brains were scanned individually using a functional magnetic resonance imaging (fMRI) scan while they engaged in the task of finding their way around the maze. ACh acts mainly in the area of the hippocampus, which is specifically related to memory, especially spatial memory.

After one trial, the participants went home and returned 3-4 weeks later, were injected with whichever solution they did not have before and were scanned again. Neither the participants nor the researcher knew who was in which group. This sort of design is common in experiments and is called a ‘randomized double-blind cross-over design.’ It is well enough controlled to show cause and effect, rather than just correlation.

Scopolamine reduced the activity in the hippocampal area and the participants in the scopolamine condition also made more errors than those who received the placebo. This shows that scopolamine decreases the ACh action in the brain, confirming that ACh is associated with spatial memory in adults as well as in non-human animals.

Among the first human subject research experiments to be documented were vaccination trials in the 1700s. In these early trials, physicians used themselves or their family members as test subjects. For example, Edward Jenner (1749–1823) first tested smallpox vaccines on his son and the children in his neighbourhood. Clearly, such an approach would not be permissible today. Indeed, for both medical and psychological research, ethical guidelines have been drawn up to protect research participants. The guidelines that psychologists follow are revised regularly by groups monitoring psychological research worldwide. Two sets of these guidelines for research with human participants are those published by the American Psychological Association (APA) and the British Psychological Society (BPS), who have also published guidelines for studies using animals. They are long documents that you do not need to read in detail, but the main point is that they have been considerably strengthened since some of the classic studies that you read about on the course were carried out.

In human research, the researchers have to ensure that the following guidelines have been met:

the participants must have given informed consent

they should not be deceived, or any deception necessary for the validity of the findings should be minimal and revealed at the debrief

confidentiality must be maintained

they should be debriefed after the study

they should be allowed to with draw themselves and their data at any time

they should not be harmed psychologically or physically

In the UK, a government licence is needed to carry out animal research, and, the BPS has identified the ‘3 Rs’ of animal research. These are to:

Replace animals with other alternatives.

Reduce the number of individual animals used.

Refine procedures to minimise suffering.

We consider the ethics of animal research later in this chapter.

Ethical considerations are part of the planning and carrying out of research. They also apply to the use of data and publication. A question on ethical considerations is not requiring you to answer with a critique of the most unethical study you know, but rather to put yourself in the researcher’s place and consider the one or two prime concerns they will have had before, during and after the study. How could they keep the participants’ identities and data confidential? How could they ensure that the participants really understood the information on the informed consent sheet? How could they protect their participants from any stress while under experimental conditions? Think of Antonova et al.’s experiment (above); how could they ensure that the participants did not become too disturbed by being injected with an unfamiliar chemical and having their brain scanned?

Case studies taking a biological approach often use participants who may not be able to make an informed decision about whether to take part in a research study or not. As a consequence of this, a partner or family member usually gives consent instead. Clearly, this raises ethical issues about participants being used in research who do not have the mental capabilities to make a reasoned decision about their participation.

The development of advanced modern technology has allowed researchers to build a more accurate understanding of how our brains work. These technological methods include the encephalogram (EEG), magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). Although all of these techniques ultimately have the same goal in that they aim to produce coherent representations of the brain, they do differ in the type of image produced: MRI scans can only show brain structure and therefore produce static images, while EEG shows brain activity, and PET and fMRI can show structure and also brain activity as it changes over time.

MRI scans represent an advancement in technology because they are able to produce static 3-D images of the brain. MRI scanners use a magnetic field and pulses of radio wave energy to make pictures of organs and structures inside the body, including the brain. This technique is used to find problems such as tumours, bleeding, injury, blood vessel diseases or infection. Physicians also use the MRI examination to detect brain abnormalities in patients with dementia, a disorder that can cause confusion or memory loss. It has a high sensitivity for detecting the presence of, or changes within, a tumour. In addition, MRI scans are highly useful to neuropsychologists studying brain-damaged individuals because they have the advantage of being more detailed and in 3-D format hence localization of damage is more precise. This could be critical in determining how far small brain areas are involved in particular cognitive processes. One of the limitations of MRI scanning is that people with heart pacemakers, metal plates or screws in their bodies may not be scanned. This could, therefore, mean the loss of potential participants in psychological studies. Although this issue would not be a large-scale problem, it may become problematic if a patient with a unique psychological deficit not previously recorded could not be scanned to assess how their brain damage correlates with their psychological difficulties. Also, some people suffering from claustrophobia, people with dementia and children may find it difficult to tolerate the procedure. If people move during the scan, the images are unclear and difficult to interpret reliably.

Focus on Research - example of a study using MRI scans

Maguire et al. (2000) used MRI scans to compare the brains of licensed London taxi drivers, who have to remember a map of the streets of London in order to gain their licence, to a control group who did not drive taxis. The results showed that there was a significant difference in the size of various parts of the hippocampus of taxi drivers: the posterior hippocampus was larger in taxi drivers (especially on the right side), whereas the anterior hippocampus was larger in control subjects. The volume of the hippocampus also correlated with how long the subject had been a taxi driver. This evidence supports the theory that the posterior hippocampus in each side of the brain stores a spatial representation of the environment and is ‘plastic’, responding to the individual’s needs in response to their environment. This study also provides evidence of localization by illustrating specific brain locations dedicated to spatial mapping of the environment. (See below in Section 3.3 Neuroplasticity for full details of Maguire’s study).

fMRI is non-static brain imagery that uses magnetic resonance imaging to measure the tiny metabolic changes that take place in an active part of the brain. When neurons in a particular region are active, more blood is sent to that region. The fMRI machine maps changes in the brain’s metabolism (chemical changes within the cells) and uses radio waves and magnetic fields to generate a 3-D time map to show precisely which parts of the brain are active during a wide range of tasks. As well as investigating the correlation between behaviour and brain activity in certain areas, fMRI scans are also used to help assess the effects of stroke, trauma or degenerative disease (such as Alzheimer’s disease) on brain function. The medial temporal lobe area, which includes the hippocampus and amygdala, has been investigated in patients with Alzheimer’s disease. With the use of fMRI scans and post-mortem brain studies, cognitive neuroscientists have identified that this is the first area of the brain to show damage in this disease.

Antonova et al. (2011) used fMRI scans to detect neural activity in the hippocampal area (see Section 2.3, above).

PET scanning is a type of nuclear medicine imaging. Nuclear medicine is a branch of medical imaging that uses small amounts of radioactive material to diagnose and determine the severity of a variety of brain diseases, including cancers and neurological disorders. A radioactive substance is injected into the patient. This is usually a form of sugar that produces measurable gamma rays as it is metabolized in the brain. A PET scan detects these rays and turns them into computer images of brain activity. These scans are used to examine functions such as blood flow, oxygen use and sugar (glucose) metabolism, to help doctors evaluate how well the brain is functioning.

Because PET scans are able to pinpoint molecular activity within the body, they offer the potential to identify a disease in its earliest stages. They are useful for showing abnormalities in brain activity levels in diseases that do not show structural changes until much later, like Alzheimer’s disease. Though less precise than fMRI scans, for example, they are a useful tool in early diagnosis of brain disease.

In psychological research, PET scans have proved highly useful in monitoring blood flow changes whilst participants perform tasks linked to a wide range of cognitive abilities. This has enabled researchers to detect which brain areas are more active when participants perform various aspects of psychological tasks.

Focus on Research - example of a study using a PET scan - Tierney et al. (2001)

Tierney et al. (2001) carried out a case study on a 37-year-old male patient they referred to as M.A. While participating in a language study that involved having your brain scanned with MRI, researchers noticed that M.A had a lesion in the left hemisphere of the brain. This area of the brain is responsible for our speech and language. The lesion probably developed when he was two years old and he suffered from encephalitis (an uncommon but serious condition in which there is swelling in the brain).

It’s logical to assume that if the language areas of the brain were damaged before M.A could learn to talk or read fluently, then he would suffer from speech and language problems. However, this was not the case and M.A’s language skills had developed normally. In fact, he was bilingual – he spoke English and also used American sign language (ASL) because both of his parents had severe hearing problems. He used ASL at home and spoke English normally with other people.

Tierney et al. hypothesized that this could be because other areas of M.A.’s brain had taken over the function of speech production to compensate for the damaged speech areas in the left hemisphere. To test this, M.A. was compared with 12 bilingual (English and ASL) participants. PET scans were used when the participants were participating in speech tasks. The speech tasks involved the participants simply recounting an event or a series of events in detail.. Unlike most sign language users, M.A.’s right hemisphere was highly active, suggesting that this hemisphere had probably taken over speech production when the left hemisphere was damaged. This type of change is evidence of neuroplasticity. For example, some neural connections become stronger when a particular skill is practiced, such as juggling (see Draganski et al., 2004, in Section 3.3 below).

In M.A.’s case, the researchers concluded that his brain structure had been changed in the right hemisphere, with more connections than normal in his right frontal lobe to allow him to produce language, possibly at the expense of other skills normally localized in the right hemisphere.

Neuroplasticity is not just a feature of recovery after a brain injury because non-injured brains also undergo such neural network rearrangement as a result of influences from the environment. The fact that we do not live in a vacuum and interact on a daily basis with various aspects of the environment shows the fundamental neuroplasticity that must be occurring in the brain in order for us to adapt to life’s demands.

Localization of function refers to the theory that the mechanisms for thought, behaviour and emotions are located in different areas of the brain. To what extent certain functions are located in their own areas, and activity in this area can therefore be seen as evidence of a behaviour, thought or feeling, is the subject of localization of brain function.

There is a long history to the theory of localization of function in the brain. The concept is directly traceable to the ideas of a German physician, Franz Josef Gall (1758–1828), who introduced phrenology – the science (now seen as a pseudo-science) of inferring a person’s behaviour from the shape of their skull. While this has been discredited, the assumption that certain parts of the brain are responsible for specific behaviours is still valid.

As mentioned in the introductory section of this chapter, the French neurologist Paul Broca located the ability for speech production in the left frontal lobe, a region that came to be known as Broca’s area, as early as 1861 (Broca 1861a, 1861b). Given that the scientific techniques available to physicians like Broca to study the brain were limited at the time, the only recourse to examine the location of brain damage was to wait until a patient died in order to perform a postmortem examination.

One of Broca’s most widely cited case histories is that of Louis Leborgne who was 51 when they met and had been admitted to hospital suffering from gangrene. The patient earned the nickname of ‘Tan’ because this was the only word he could produce. He was also paralysed down the right side of his body due to what is believed to be a left hemisphere stroke. Leborgne died only a few days after meeting Broca for his initial assessment and Broca therefore performed an autopsy that revealed a left frontal lobe lesion. This therefore confirmed Broca’s assertions that this area of the brain was significantly involved in speech production and damage in this location can result in the speech production deficit known as Broca’s aphasia.

The investigation of Louis Leborgne highlights the value of the case study, as well as the autopsy in psychological research, and indeed the case study approach has formed the cornerstone to localization of function research ever since Broca’s pioneering studies of brain-damaged patients. However, recent modern advances in brain science with regard to neuroimaging technology have complemented the case study approach. In an ironic twist of fate, Leborgne’s preserved brain was subjected to brain imaging over 140 years after his death in a recent study by Dronkers et al. (2007). This study was able to demonstrate in more intricate detail the extent of Leborgne’s brain damage and served therefore as a neat illustration of the virtues of brain imaging technology being used in conjunction with patient case studies and autopsies.

Limitations of the localisation approach

Although adopting a localization approach in the quest to understand the brain has undeniably meant that scientific knowledge about the brain and behaviour is currently very advanced, other researchers have urged caution in adopting what they feel is a ‘jigsaw’ type perspective of the brain. The complexity of cognitive processes in terms of how they interact and influence each other cannot be ignored hence more holistic accounts of how the brain works should be used in conjunction with the localization approach. Karl Lashley, an eminent neuroscientist, was an early champion of a more holistic viewpoint of brain function and, in the 1950s, demonstrated the validity of this in a study with rats who had undergone lesioning. The rats in this study learned to navigate mazes and Lashley found that if he removed varying amounts tissue in the cortex of different rats in different brain areas (sometimes up to 50%), this did not affect their learning of the maze. This study, therefore, indicated that memories were widely distributed throughout the cortex and not localized to a particular area. Lashley’s fame in the neuroscience field led other researchers to also adopt an anti-localization approach, but research has since reinforced the idea that there are many specialized brain areas for different processes. Lashley and his supporters were misled in the sense that very complex tasks like learning a maze are going to use a large number of different neural networks in order to deal effectively with the task and this is why large scale lesioning (destruction of certain areas of the brain) in the rats did not impair the rats’ maze navigation skills.

Other researchers have also criticized the idea of localization because it implies that specific brain areas are specialized for particular processing and that other brain areas cannot, therefore, take over their functions. However, research into the brain’s adaptive and flexible capabilities has challenged this more static view of brain function and in the next section you will read more about these ideas and learn about studies that have demonstrated the extent to which the brain shows plasticity.

Both Maguire et al. (2000) and Draganski et al. (2004) may be used for localization of function (see below).

Ask Yourself What are some of the challenges of researching people with brain damage?

Neural networks

The examples above all demonstrate that many brain functions are localized in their own specific parts of the brain. However, the brain is far from ‘static’ because research has shown that complex neural networks can also be modified and changed in a process known as neuroplasticity . This process is of particular significance in young children during their early brain development. The very rapid development of new neural networks is essential early in life as a considerable period of learning occurs at this stage.

Earlier, you encountered the study by Maguire et al. (2000) which demonstrated how repeatedly encountering the same environmental information on a regular basis over time leads to significant neural network changes in order to accommodate such environmental information. Maguire et al.’s research clearly shows how environmental demands can alter neural networks so that they become more adapted to cope with specialized tasks.

You can use Maguire et al.’s study and Draganski et al’s (2004) research as key studies in this section on neuroplasticity, just as you can in the section on brain imaging techniques and MRI scans, and the section on localization (above).

Focus on Research – neuroplasticity and neural networks - Maguire et al. (2000)

From the results of previous research, mainly on animals, Maguire et al. believed that there may be a correlation between spatial memory and the size and density of the neural networks in the hippocampus, suggesting localization of this function (as well as neuroplasticity and the growth of neural networks). They conducted the following quasiexperiment to investigate this the ability of the brain to change in terms of volume of grey matter dependent on learning and experience.

The participants were 16 healthy, right-handed male licensed London taxi drivers who had passed ‘The Knowledge’, a test of spatial memory. The age of the sample ranged from 32- 62 years with a mean age of 44. They had all been taxi drivers for at least 18 months, with the most experience being 42 years of taxi driving.

The participants were placed in an MRI scanner and their brains were scanned. The focus of the scan was to measure the volume of grey matter in the hippocampus of each participant and then to compare it to the scans of the control group. The grey matter was measured using voxel-based morphometry (VBM) which focuses on the density of grey matter and pixel counting. The taxi drivers’ MRI scans were compared with pre-existing MRI scans of 50 healthy right-handed males who were not taxi drivers.

The researchers found that the posterior area of the hippocampi, especially the right hippocampus, of the taxi drivers showed a greater volume of grey matter than that of the controls, who had increased grey matter in their anterior hippocampi compared to the taxi drivers. They also carried out a correlational analysis and found that the growth in the right posterior hippocampal neural networks showed a significant positive correlation to the length of time spent as a taxi driver.

They concluded that the posterior hippocampus may be linked to spatial navigation skills built up via learning and experience. The correlational analysis of time spent as a taxi driver linked to increased volume of hippocampal grey matter lends validity to the idea of neuroplasticity due to learning and experience, and counters the argument that the taxi drivers may coincidentally have had larger than usual hippocampi.

Neural pruning

Not all of the neural changes will be needed as a child gets older so child development is not only characterized by rapid neural growth but also by significant neural pruning (reduction in density) as some neural pathways in the brain are no longer needed. It was thought that such widespread pruning only occurs in early childhood but research has shown that during adolescence another extended period of pruning occurs, and indeed our brains continue to change, albeit to a lesser extent than in childhood, throughout our lives.

For example, when we learn a new skill, like how to play the piano, our neural networks grow and become denser in certain parts of the brain. This is called neurogenesis. However, if we then stop playing the piano, a few months later neural pruning will take place and we will lose those new neural connections, giving some truth to the saying ‘Use it or lose it.’

Focus on research – neuroplasticity and neural pruning – Draganski et al. (2006)

Draganski et al. (2004) conducted a field experiment to determine whether, after learning a new motor skill, there would be both structural and functional changes in the brain. The researchers used MRI scans to determine if changes occurred in the brains of people learning to juggle over a span of three months. The participants were randomly allocated to two groups (juggling and non-juggling/control) and had their brains scanned three times: before learning to juggle, after three months of learning to juggle, and three months after they had ceased juggling. These scans were compared to a control group of non-jugglers.

Whilst there was no difference in brain structure between the two groups shown in the first scan, the second scan, at three months, showed that the group of jugglers had two areas of the brain that were significantly different in size from that of the control group. This difference became smaller after three months of no juggling, at the third scan.

The conclusion was that the action of watching balls in the air and learning to move in response to them strengthened the neuronal connections in the parts of the brain responsible for this activity. However, the differences were temporary and relied on continuing the activity or else neural pruning took place when the connections were no longer used. Although this was a field experiment, as the juggling practice took place under natural conditions, there was random allocation to groups and standardization of measurement, so this was a well - controlled experiment that would have high internal validity.

Neurons in certain brain areas are specific in which neurotransmitters they release and receive. This means that their action can be affected by particular drugs, both medical and recreational, before their release into the synapse and also during their uptake by the receiving neuron or reuptake by the releasing neuron.

Neurotransmission

This is what neurotransmitters do. They communicate between nerve cells (neurons). There can be as many as 100 billion neurons in the human brain and they form trillions of connections between each other. Neurons carry information as electrical impulses but neurons communicate with each other by an additional chemical process involving neurotransmitters These are chemicals that are released across a gap between the neurons called the synapse and the neurotransmitter is then picked up by the receptors of another neuron.

Excitatory and inhibitory synapses

Every neuron has receptors designated for each neurotransmitter that works like a lock and key mechanism, and this is how the neurotransmitter binds to the neuron. When the neurotransmitter combines with a molecule at the receptor site it causes a voltage change at the receptor site called a postsynaptic potential (PSP). One type of PSP is excitatory and increases the probability of producing an action potential in the receiving neuron. The other type is inhibitory and decreases the probability of producing an action potential.

Whether or not a neuron fires depends on the number of excitatory PSPs it is receiving and the number of inhibitory PSPs it is receiving. PSPs do not follow the ‘all or none’ law.

Antonova et al. showed that ACh is excitatory in synapses in the medial temporal lobe and hippocampus.

Agonists and Antagonists

All neurotransmitters are natural agonists that are endogenous (produced by the body and act inside the body). They bind to synaptic receptor neurons to generate either an excitatory or inhibitory PSP, as we read above. Chemical agonists are substances that bind to synaptic receptors and increase the effect of the neurotransmitter. They do this by imitating the neurotransmitter. If you thib nk of the ‘lock and key’ mechanism, agonists oil the lock and make it easier for the neurotransmitter to have an increased effect.

Alcohol, for example, binds with dopamine receptor sites, causing dopamine neurons to fire. The firing of these neurons results in the activation of the brain's reward system - the nucleus accumbens, and a feeling of pleasure.

Antagonists are chemical substances, both naturally found in food, and medicines, and artificially manufactured. They also bind to synaptic receptors but they decrease the effect of the neurotransmitter. Therefore, if a neurotransmitter is excitatory, an antagonist will decrease its excitatory characteristics. This is like putting chewing gum in the lock so it sticks and the key is unable to turn well.

Antonova (2011) demonstrated that ACh is an agonist in the medial temporal lobe area, and also scopolamine is an antagonist for ACh and decreases its action, reducing spatial memory ability.

The table below gives a brief description of the major neurotransmitters (there are others) and the areas of the brain where they take effect. (Again, there are others).

Table 4.1 Some major neurotransmitters and their functions

Focus on Research – serotonin - Walderhaug et al. (2007)

Walderhaug et al, (2007) aimed to investigate the role of serotonin on mood regulation and impulsivity and the role of the 5-HTT gene in the brain. conducted a study on healthy participants using a technique called acute tryptophan depletion, which decreases serotonin levels in the brain. Serotonin is a hormone in the body and a neurotransmitter in the brain, but it cannot cross the blood-brain barrier. Therefore it has to be made in the brain, and tryptophan, an essential amino acid found in animal protein can cross the blood/brain barrier and is the main building block of serotonin.

A volunteer sample of 39 men and 44 women participated in a randomized, double-blind experimental study using a technique called acute tryptophan depletion, which decreases serotonin levels in the brain. Behavioural measures were taken of impulsivity and mood.

The study showed that men exhibited more impulsive behaviour as a result of the serotonin depletion but the technique did not alter their mood. Women, on the other hand, reported how their mood worsened and they also showed signs of more cautious behaviour, a response that is linked with depressive behaviour. This means that women and men appear to respond differently to neurochemical changes.

It is already known from a significant amount of research in this field that reduced serotonin transmission contributes to the functional changes in the brain associated with a major depressive disorder (MDD) and this study, therefore, reinforces such findings. Furthermore, in the female participants, it was shown that the tryptophan depletion affected a region of the SLC6A4 gene, a gene which influences the serotonin transporter (5-HTT) in the synapse.

Such findings have contributed to the development of most of today’s most popular antidepressants being designed to temporarily block the serotonin transporter so that serotonin remains in the synaptic gap for longer.

It is also known that people with MDD are frequently found to have less impulse control, and this observation was also reinforced in this study. However, this was the first study to identify sex differences in the way that men and women react to reductions in serotonin function, specifically in terms of their mood and impulsivity.

Focus on Research – acetylcholine – Martinez and Kesner (1991)

Martinez and Kesner (1991) aimed to investigate the role of the neurotransmitter acetylcholine (ACh) in spatial memory formation. They carried out an experiment on laboratory rats who were trained to run a maze.

The rats were then divided into groups as follows:

Group 1 was injected with scopolamine which blocks ACh receptor sites and therefore reduces the availability of ACh.

Group 2 was injected with physostigmine which blocks production of cholinesterase, an enzyme which cleans up ACh from the synapses. This injection increased the availability of ACh.

Group 3 was the control group and received no injections.

The investigators found that Group 1 rats (scopolamine, less ACh) made more mistakes and were slower as they ran the maze compared to Group 2 rats (physostigmine, more ACh) that ran more quickly through the maze and made fewer mistakes. So, Group 1 was slower and made more mistakes than the control group. Group 2 was faster and made fewer mistakes than the control group.

The investigators concluded that ACh is a neurotransmitter that boosts spatial memory.

Remember that Antonova (2011) conducted a similar experiment to this, but on humans, and concluded the same. If you are answering an SAQ on the influence of one neurotransmitter on behaviour, do not use an animal study. An animal study may be used as supporting evidence for a human study in an ERQ. Both Martinez and Kesner and Antonova et al. also show that scopolamine acts as an antagonist for ACh.

Ask Yourself How does Martinez and Kesner’s study show the value of animal research when investigating the brain and human behaviour?











inhibitory neurotransmitter (synapse) affects behaviour

Hormones are chemical messengers that are secreted (secrete = given out) by glands. The difference between a hormone and a neurotransmitter is that, while both are secreted inside our bodies, hormones are produced by endocrine glands and neurotransmitters are produced within neurons when triggered by an electrical impulse. Hormones enter directly into the bloodstream, while neurotransmitters are secreted at neuron synapses. However, it is important to be aware that some chemical messengers can act both as hormones and neurotransmitters. Adrenaline is an example: it is secreted as a hormone in the body by the adrenal medulla (at the centre of each adrenal gland, just above the kidneys) when we encounter a stressful situation. Its purpose is to prepare the body for a fight or flight response by increasing the heart rate. However, it is also used by adrenal-specific neurons in the brain in the control of appetite for example.

Unlike neurotransmitters, which act in a split second, a hormone may take several seconds to be stimulated, released and reach its destination. If an immediate behavioural reaction is required, neurotransmitters and the nervous system play the major role. For a slow, steady response over a period of time, we have hormones.

Testosterone is primarily secreted in the gonads (in the testes of males and the ovaries of females), although small amounts are also secreted by the adrenal glands. It is the main male sex hormone and plays a key role in the development of male reproductive tissues such as the testes and prostate as well as promoting secondary sexual characteristics such as increased muscle and bone mass and hair growth. On average, an adult human male produces about ten times more testosterone than an adult human female, although there is a wide variation in the amounts, and there may be overlaps between high testosterone-producing females and low testosterone producing males.

Studies have connected testosterone with aggression in both males and females, but Archer (1994) reviewed the research, and concluded that there was a low positive correlation between testosterone levels and aggression in males, but a much higher positive correlation between testosterone levels and measures of dominance. While hormones may influence our responses, the social and cultural contexts must not be ignored.

Ask Yourself Which sociocultural factors are likely to be involved in aggressive behaviour?

Focus on Research – testosterone – Carré et al (2016)

Carré et al. (2016 )noted that research into the link between aggression and testosterone levels has produced inconsistent results over the last few decades. In this experiment, the researchers aimed to find out whether aspects of personality would affect aggressive responses to a game. 121 healthy male participants were randomly allocated to two groups, where one group received a placebo and one group an injection of testosterone. It was a double-blind technique wherein neither the experimenters nor the participants knew which injection they had received.

All of the participants then underwent a decision-making game that was designed to assess aggression after social provocation within the game by a partner (actually the computer).

Measures of personality with regard to dominance and impulsivity traits were assessed using questionnaires. The researchers found that an increase in testosterone levels alone was not enough to provoke aggression. Only those men who had received additional testosterone and had scored high in dominance and low in impulse control exhibited higher aggression than the control group and the rest of the testosterone group who did not possess these personality characteristics.

Focus on Research – testosterone – Nave et al. (2017)

Similarly, Nave et al. (2017) investigated the effect of testosterone on cognitive reflection in males. It would seem logical that as testosterone interacts with already low impulse control and high dominance to produce aggression, maybe it also reduces cognitive reflection. Before the 243 healthy male participants randomly received either testosterone or a placebo in a single dose of gel applied to the skin, they gave a baseline saliva sample. They then went away for a few hours to give the testosterone time to stabilise in the bloodstream, returned and gave another sample to check for the level of the hormone. After this all the participants took the Cognitive Reflection Test (CRT) that tested their ability to override impulsive judgements and snap decisions with deliberate correct responses. A sample was taken during the testing and another at the end. The results showed that the participants who received testosterone had significantly lower scores on the CRT than the control group. This demonstrates a clear effect of testosterone on cognition and decision-making. It remains to be seen if the findings found in both of these experiments would be the same in females.

4.2 Pheromones and Their Effects on Behaviour

Unlike hormones, which act inside the individual body, pheromones are produced individually, but act outside the body at species level. Therefore they are sometimes referred to as ‘exogeneous hormones’. Insects and mammals possess pheromones and there is some evidence that pheromones may play a role in human behaviour, predominantly in either mating behaviour or mother-baby bonding; however, none is conclusive. A discussion of the effects of pheromones on behaviour is a useful exercise in critical thinking.

One of the newest areas of research in psychology is the field of evolutionary psychology, an area we will be revisiting later in the biological chapter, in the section on genetics and behaviour. Evolutionary explanations of behaviour argue that some of the behaviours we witness in modern life are the legacy of genetic adaptations that contributed to survival in of the species during the time of our earliest ancestors. Although this field in psychology raises a number of practical problems in assessing how far evolutionary processes affect modern behaviour, it also raises many interesting questions regarding how we act.

One behaviour that is argued to be adaptive is the choice of a suitable mate. It is important that we choose a mate whose genes are sufficiently different from our own to avoid any problems that could be created by ‘in-breeding’. This is why there is a strong feeling against marrying people to whom you are too closely related and why brother–sister marriages are illegal in most countries. Some researchers have argued that one way in which we can identify if a person is genetically distant from ourselves is through pheromones. These are chemical hormones that, despite not having a smell, are detected by the vomeronasal organ, which lies at the base of the nasal cavity, in the soft tissue and just above the roof of the mouth.

Pheromones can only act within species and in 1959 the first to be detected was in female silkworm moths who produced the pheromone bombykol to attract males. However, later research in humans suggested that our behaviour can also be influenced by pheromones being emitted from other humans. McClintock (1971) published research that showed how women living in dormitories together often develop synchronous menstrual cycles over time. This study proposed that a pheromone emitted by each woman caused the synchronisation but did not suggest what chemical structure the pheromone may have. It has been later criticised and has been difficult to replicate successfully.

MHC (major histocompatibility complex) is a group of genes that, while possibly not pheromones, can be smelt in sweat, and if attraction to those with different MHC than our own is followed by mating (a big ‘if’), this maximises the immune responses in offspring, making them stronger.

Focus on Research – putative (possible) human pheromone – Wedekind et al. (1995)

Wedekind et al. (1995) conducted a study to investigate whether females prefer male odours from males with a different MHC from their own. This could suggest an influence of pheromones on human adults. In this study, 44 male students were asked to wear the same T-shirt during two consecutive nights. The T-shirt was kept in a plastic bag between the two nights and the men were asked to remain as odour-neutral as possible by avoiding sexual activity, smoking and the use of strongly perfumed products and foods that produced strong odours. The mean age of all participants was 25 years old and prior to the study, all male and female participants had been classified in terms of their immune system similarity via a specialised blood test.

The day after the men had worn their T-shirt for the second night, 49 female students were each asked to rate six T-shirts for pleasantness and odour intensity. three of them had been worn by males with a similar MHC to them and the other three by males with a very different MHC from them. The females had to smell the T-shirts by via a triangular hole cut into a cardboard box in which the T-shirt had been placed. Each T-shirt was assessed by the females according to how intense and how pleasant they found their smell.

The researchers found that a woman whose MHC was different from the male’s MHC found his body odour to be more pleasant than women with a similar MHC to the male’s. This finding, however, was opposite if the woman was taking the oral contraceptive pill: these women were more attracted to males who had a similar MHC to their own. Women are normally attracted to males with a different MHC than their own, but the contraceptive pill may interfere with natural mate choice based on MHC dissimilarity. Because the women who were on the contraceptive pill preferred men with similar MHC to their own, as would be found in men with a family connection to them, for example, Wedekind et al. speculated that this reflected a hormonally-induced shift owing to the pregnancymimicking effect of the pill, leading to increased association with kin who could assist in childcare.

Roberts et al. (2008) followed up on Wedekind’s findings and tested directly whether taking a contraceptive pill altered odour preferences. The procedure for the male participants mirrored that of Wedekind et al. and all participants undertook blood tests to assess immune system similarity. This study, however, used a longitudinal design with the females being divided into two groups. The first group of women were tested before and after using the contraceptive pill, whilst the second group of women formed a control group (no contraceptive pill use) but attended the testing sessions in comparable intervals to the contraceptive use group.

The findings supported those of Wedekind et al. in that there was a significant preference shift towards MHC similarity between males and females associated with pill use, which was not evident in the control group. Both Wedekind et al. and Roberts et al. concluded that contraceptive use may be interfering with natural biological mating mechanisms if dissimilarity of MHC (which is possibly a pheromone) between mates plays a role in maintaining attraction between partners within a relationship.

Focus on Research – argument against human pheromones – Doty (2010)

Despite the evidence outlined above, other researchers have disputed completely the idea that humans emit pheromones that can be detectable by other humans. One of these researchers is Richard Doty who, in his book The Great Pheromone Myth, discussed his arguments against the existence of human pheromones. Doty (2010) states that one major problem in this area of research is that no current scientific definition exists about what a mammalian pheromone actually is. Although many scientists have claimed that pheromones play an integral part in not only human mate selection but also other behaviours such as emotion and mood, Doty raises the point that human pheromones have not been chemically isolated.

He also speculates on the dangers of using research on insects that has shown evidence of pheromone action and using these findings to assume that such pheromonal processes must also exist in humans. In addition, Doty objects to the idea that one chemical can influence behavioural changes in other members of the same species given that there are multiple chemicals in the environment influencing behaviour at any one time.

Riley (2016) analysed the claims for the existence of human pheromones and, like Doty, also believes that they do not exist. Riley further states that the human vomeronasal organ has no nerve links to the brain and is therefore unlikely to influence our behaviour.

Ask Yourself What challenges do you think researchers face in trying to isolate possible human pheromones?

Genetic information is contained in chromosomes and each human has 23 pairs of chromosomes (tightly-wound strands of DNA) in each of their cells and one of each of these pairs is from each parent. Our DNA, therefore, forms a blueprint for the structure and functions of our body. The term genome is used to signify all the genes an individual possesses. Genes contain biological instructions to form protein molecules from amino acids. Proteins are essential to life because they are the building blocks of our brain and body. It is no surprise therefore that psychologists have taken an interest in how genetics may affect behaviour. The development of new techniques as a result of advances in scientific technology has meant that this area of psychology research has been able to advance in recent years.

Research has indicated that the genes in our DNA are not all active at the same time and can be ‘silenced’ or ‘de-silenced’, i.e., switched on or off. This process is called gene regulation and leads to differences in gene expression. In other words, processes within cells regulate which genes are expressed or active. To switch a gene off, and therefore prevent it from making the protein it was designed to produce, cells can use chemicals in the body called methyl groups and initiate a process called methylation to block a gene’s effects. However, a gene can be switched back on by the reverse process of demethylation. The study of how genes are switched on and off is called epigenetics. It is important to note that the genes are not permanently altered but their ability to influence our biology is manipulated: the genes will work normally again once switched back on. During development in children, however, if certain proteins are no longer needed the methylation process will be permanent. Gene expression, therefore, plays an extensive role in the developing brain.

Research has also shown that negative events during childhood can influence gene expression, as shown in the Suderman et al. (2014) study.

Focus on Research – epigenetics – Suderman et al. (2014)

Research by Suderman et al. (2014) demonstrated that 12 adults who had suffered childhood abuse were more likely to show methylation in their DNA compared to a control group of 28 who had suffered no such abuse. The participants were 45 year-old males and their blood DNA was analysed.

In particular, the study showed that there was increased methylation of the gene PM20D1 in the sample who had suffered abuse. This gene is responsible for the metabolism of amino acids and is associated with control over eating habits. Those with childhood abuse were also shown to have long-term associations with negative health outcomes, specifically, a greater prevalence of obesity among those who reported physical abuse in childhood. This supported previous research that links this gene with childhood abuse and increased obesity as an adult. This finding, therefore, shows how an environmental trigger like abuse can contribute to switching off a gene which contributes in some way to a person’s food intake. Evidence from this study indicates that there is a correlation or relationship between the methylation of gene PM20D1, child abuse, and eating habits in adults. This suggests that the interaction between genes and environmental influences can predispose a person to behave in a certain way.

Suderman et al.’s epigenetic study provides evidence for how gene expression can be affected by traumatic environmental events. Other studies with animals have also found similar results as shown in the study by Weaver et al. (2004, also referenced in some texts as Meaney et al., 2004) which investigated maternal behaviour in rats.

Focus on Research epigenetics - Weaver et al. (2004)

Weaver et al. (2004) investigated stress responses of rat pups (babies) who had received vigorous licking and grooming from their mothers in the first ten days after birth and compared them to rats who had not received much attention from their mothers. The stress response was measured by placing each rat into a small tube for twenty minutes and measuring their reaction to this confined situation. The stress hormone corticosterone (a glucocorticoid) was measured in each rat.

It was found that the rats who had more attention from their mothers had lower levels of corticosterone than the rats who had not. It could be argued that the reason these differences emerged was that the rats inherited their temperament from their mothers: the calmer rats may have had calmer mothers who as a result of being calmer in temperament were able to engage in high attention maternal behaviour with their offspring. To test this possibility the researchers carried out another study in which the offspring of anxious rats were placed with calmer mothers who frequently licked their pups, and the offspring of calmer rats were placed with more anxious mothers who did not engage in high levels of maternal licking. It was found that the reactivity to stress depended on adoptive mother behaviour and not biological mother behaviour.

This is an example of epigenetics and is explained by gene expression . The researchers showed that the glucocorticoid receptor genes in the brain are methylated (switched off) when mothers neglect their pups and these pups went on to become worse mothers. Rat pups raised by nurturing mothers were less sensitive to stress as adults. Acquired epigenetic modifications can be inherited and passed on to offspring; this is not just learned behaviour.

We can conclude from this section therefore that although we are the product of the genetic information received from our parents research has highlighted how far the environment can have an impact on genes through the process of gene expression.

Ask Yourself Why would it be impossible to conduct Weaver et al.’s animal study with humans?

Genetic similarity is referred to as relatedness. The greater the genetic similarities between two individuals or a group of individuals the higher the degree of relatedness.

(Source: IB Psychology Guide )

Twin studies

An awareness of the degree of relatedness between MZ and DZ twins, siblings, parents and children and parents and adopted children provides a critical perspective in evaluating twin or kinship studies.

As described above, psychologists have more recently been able to gain insights into how gene expression plays a role in behaviour, but a long-standing traditional technique that is still widely used today is to study how behaviour varies according to the degree of genetic similarity between relatives. This is called relatedness. As genes cannot ethically be manipulated in humans to see the effect on behaviour, family-based studies are an ideal way to assess how genes influence behaviour. Such studies are therefore correlational in nature.

As mentioned earlier, in Section 2.1, any correlational studies into the relationship between genes and behaviour measure the concordance rate of a personality characteristic or a behaviour between individuals. This means that they look at the extent to which the pairs of individuals (usually twins, both identical/monozygotic and non-identical/dyzygotic) share a behaviour. A concordance rate of 1 for a behaviour is 100% concordance, which in real life is impossible to achieve. It would mean that one twin behaved exactly the same as or had exactly the same intelligence or attitude as the other. Concordance rates of 0.7 (70%) are considered extremely high. A zero concordance rate means that there is no correlation at all between two people’s behaviour. Twin studies can be carried out in two ways: they can assess twins who have been reared together or they can study twins who have been separated and raised in different environments. The latter strategy is the most desirable in terms of research because if there is a concordance rate for certain behaviours between the twins that is higher than the rate in siblings (brothers and sisters) who are not twins, this suggests a genetic influence as they are being raised in different environments. However, the strategy of testing twins reared apart is extremely difficult to implement in reality because twins are so rare and twins raised separately are even rarer.

You will explore correlational studies as part of the biological explanations for mental disorder when you study Abnormal Psychology.

Focus on Research – correlational (twin) study – McGue et al. (2000)

McGue et al. (2000) investigated the genetic and environmental influences on adolescent addiction to tobacco and marijuana. They interviewed 626 pairs of male and female twins born in the same year. Males: 188 identical (monozygotic, MZ) and 101 non-identical (dizygotic, DZ). Females: 223 MZ and 114 DZ. They were interviewed about their history and experience of legal (tobacco) and illegal (marijuana) drug use, details of their home life; and they also completed a questionnaire.

The researchers found a slight heritability for marijuana use of 10% -25%, with no significant differences between males or females. But tobacco use showed a heritability of 40%-60%. However, the importance of shared environment was also a prominent finding: the participants with a well-established habit and history of drug-taking (both legal and illegal) reported that such drugs were a regular part of family life, with reports of parents or family members openly taking drugs, and drugs being a normal part of the home environment.

They concluded that the environment appeared to be more influential in determining drug use than genetic inheritance.

Focus on Research – correlational (twin) study – Kendler et al. (2006)

Kendler at al. (2006) conducted a very large Swedish twin study with 15,493 complete twin pairs listed in the national twin registry. The researchers used telephone interviews over a period of 4 years to diagnose major depressive disorder (MDD) on the basis of (a) the presence of most of the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) symptoms or (b) having had a prescription for antidepressants.

The researchers found an average concordance rate for MDD across all twins was 38%, in line with previous research. They also found no correlation between the number of years that the twins had lived together and lifetime major depression, suggesting this was a true heritability rate. The rate among female monozygotic twins was 44% and amongst males 31%, compared with 16% and 11% for female and male dizygotic twins respectively. If the disorder was purely genetic, we might expect the monozygotic concordance rates to be much higher. But the difference between monozygotic and dizygotic concordance rates is enough to indicate a strong genetic component.

The difference in concordance rates between female and male twin pairs is interesting. The findings suggest that the heritability of MDD is higher in women than in men and that some genetic risk factors for MDD are sex-specific.

Limitations of twin studies

Studies into twins raised apart have weaknesses that must be taken into account when interpreting their results. Joseph (2002) argues that the main problem with studies of raised apart identical twins is that the investigators mistakenly compare reared-apart identical twins with raised-together identical twins, forgetting that both sets share several important similarities, which include common age, common sex, similar appearance and a common prenatal environment. Therefore, they are bound to have many similarities in behaviour. Joseph (2002) points out that the better comparison group would be with pairs of unrelated people of the same generation. Similarly, as McGue et al.’s study shows, it is difficult to disentangle environmental and genetic factors when testing twins who live together with their families.

Kinship (Family) studies

Family studies (the IB also calls them ‘kinship’ studies) investigate genetic heritability of a behaviour by looking at the incidence of a behaviour over a number of generations and controlling for other variables, such as environment. Usually, this is limited to three generations in most populations.

Focus on Research – correlational kinship (family) study – Fernandez-Pujals et al. (2015)

Fernandez-Pujals et al. (2015) conducted a large family study into the heritability of MDD. Around 126,000 individuals were asked to participate from the large Generation Scotland: Scottish Family Health Study (GS:SFHS). Each was asked to recommend one relative to the study. Participants were informed that the purpose of the study was to study the health of the Scottish population. From those invited and their relatives, 20,198 volunteered and were screened by clinical interview for symptoms of MDD. A final 2,706 were diagnosed as suffering or having suffered one or more episodes of MDD.

Correlations were calculated between relatives and the unadjusted heritability was found to be 44%. Once adjusted for same environment (i.e. taking into account all relatives who lived together and therefore for whom environmental factors could be relevant) the heritability of MDD was 28%. This is lower than for identical twins, which is to be expected, as these relatives shared 50% or lower of their genes, not the nearly 100% that MZ twins share. The heritability of recurrent MDD was significantly larger than that for single MDD and heritability for females was higher than that for males, but not significantly higher.

This evidence certainly suggests a genetic component in MDD.

Ask Yourself What are some of the difficulties involved in conducting twin and kinship research?

Evolution is the process by which plants and animals developed by descent, with modification, from earlier existing forms. These changes happen at the genetic level as organisms’ genes change and combine in different ways through reproduction and are passed down the generations.

Darwin’s evolutionary theory is based on the principle of natural selection. This means that the variations possessed by members of the same species have different values when it comes to survival. Those variations that are ‘adaptive’ will be the ones that allow those possessing them to survive and therefore will be passed on to future generations. If the environment stays the same the adaptive traits will remain in the gene pool, but if the environment changes, previous adaptive traits become less adaptive.

A well-known example is the long necks of giraffes which evolved to allow them to feed on the tops of trees and thus avoid starvation when other animals were feeding lower down. Giraffes without this adaptation died out. These useful adaptations are inherited and eventually, over a very long period of time, give rise to new species. Evolutionary psychologists working within the biological approach believe that many different human behaviours can be explained as being useful adaptations. We discuss evolutionary explanations for behaviour further on in this section.

Not all psychologists who believe in heritability (that our personality and behaviour are at least partly inherited from our parents) are evolutionary psychologists. Many twin and adoption studies have been carried out, exploring the relationship between heritability and intelligence, for example, but not all of these psychologists claim that intelligence is an adaptation that has proved useful through natural selection.

Evolutionary psychologists believe that if behaviour exists in society today, then it must be a useful adaptation that has helped us survive and reproduce, a concept known in evolutionary theory as ‘the survival of the fittest’. They also point out that despite the wide diversity of human beings in different cultures scattered all over our planet, there are some reactions that seem to be almost universal. Examples of these are the response of disgust to the smell of rotten eggs; ideas of what is attractive in a mate; fear or dislike of spiders and snakes. This is, they argue because such responses are adaptive.

Evolutionary psychologists are a long way from being able to prove a cause and effect relationship between our genetic inheritance and such responses, but they have generated some interesting ideas.

In addition, some evolutionary psychologists have argued that some phobias could have an evolutionary basis. One of the first researchers to put forward the idea that humans may have an innate tendency to fear certain animals, for example, was Martin Seligman in the early 1970s. This speculation was enshrined in his ‘preparedness’ theory (Seligman, 1971) in which he suggested that we are biologically ‘prepared’ to fear particular creatures for evolutionary reasons. In other words, fears and phobias of animals are adaptive for humans because they promote the survival of the species in some way. This idea makes more sense when we consider the environments that our ancestors needed to survive in. It is important to realise that many humans today live in some comfort compared to our ancestors. For example, we have more comfortable housing, we generally do not have to hunt for our food, and we have more sophisticated ways of protecting ourselves. Our ancestors, however, faced danger regularly and therefore it is possible that evolution equipped them with the necessary biological mechanisms to ensure their survival, i.e., innate tendencies to fear things such as strange animals, heights, deep water, etc.

The essence of Seligman’s preparedness theory, therefore, is that humans today are still influenced by their evolutionary origins and hence are more biologically prepared to be fearful of certain things. Another evolutionary mechanism that may have evolved to increase chances of survival could be the sense of disgust when we view certain stimuli. The wide-ranging study by Curtis et al. (2004) set out to test this possibility.

Focus on Research – evolutionary adaptation of disgust – Curtis et al. (2004)

Curtis et al. (2004) added a survey to the BBC Science website after a documentary had been shown about instinctive human behaviour on one of the BBC channels. A sample of over 40,000 people completed the survey. The majority of participants came from Europe but a small proportion of the sample came from the Americas, Asia, Oceania and Africa. The participants, 75% of whom were aged between 17 and 45 years old, viewed twenty photographs and rated them for the level of disgust on a Likert scale of 1-5.

The results indicated that photographs with objects representing a threat of disease were rated as more disgusting. A final question on the survey asked participants to choose with whom they would least like to share a toothbrush. Least acceptable was the postman (59.3%), followed by the boss at work (24.7%), the weatherman (8.9%), a sibling (3.3%), a best friend (1.9%) and the spouse/partner (1.8%). Sharing a person’s bodily fluid becomes more disgusting when the person is less familiar because there is viewed to be more of a disease threat from a stranger.

Curtis et al. suggested these results were evidence that disgust is an evolutionary mechanism for detecting disease thus plays a role in survival.

Earlier, we considered Wedekind et al.’s research on pheromones and how pheromones could be an adaptive evolutionary mechanism involved in mate choice. Although it was argued that the existence of pheromones in humans has been the subject of debate, other research has indicated that mate choice can be influenced by evolutionary processes like sexual selection, the process that favours individuals possessing features that make them attractive to members of the opposite sex or help them compete with members of the same sex for access to mates.

According to evolutionary theory, differences in terms of sexual selection should be expected in males and females of species (including humans) with internal fertilization. This is because if a female is unfaithful to her male partner, the male risks lowered paternity probability and runs the risk that his female mate is investing energy and resources mothering the child of a rival that does not contain his genes. Females of course don’t risk lowered maternity probability if their partner cheats on them, but they do risk losing their mate’s commitment and his resources to a rival female if he becomes emotionally committed to her.

Focus on Research – sexual selection – Buss et al. (1992)

Buss et al. (1992) investigated differences between men and women in terms of sexual selection. They asked participants (an opportunity sample of 202 undergraduate students) to vividly imagine scenarios involving either sexual or emotional infidelity by their partner. Participants’ distress while imagining these scenarios was assessed by monitoring various indices of emotional (e.g., questionnaire) and physiological arousal (e.g., sweat response).

The results showed that sexual infidelity generated the most distress in males, whereas emotional infidelity elicited the most distress in females. This difference corresponds with what evolutionary psychology would predict.

Buss et al. concluded that men are concerned that their sperm will be replaced by another man’s thus reducing the chances that genes will be passed on. They suffer from paternity uncertainty: they can’t be sure a baby is theirs if their female partner is unfaithful. A woman always knows a baby is hers but is concerned if her male partner becomes emotionally entangled with another woman, as this increases the likelihood that her mate will redistribute his resources and she and her baby may suffer.

This study, therefore, illustrates differences between male and females in terms of sexual selection in line with what would be predicted in evolutionary theory.

Limitations of evolutionary psychology

Evolutionary psychology has been accused of biological reductionism, reducing everything to a genetic level and ignoring human free will and the complexity of human behaviour. Evolutionary psychologists have responded to this by saying that it is the popularisation of their theory, rather than the theory itself, that has led to these criticisms. Just because they are trying to trace human behaviour back to its functional origins does not mean they do not acknowledge its complexity.

In addition, it is important to be cautious about interpreting the results of research in this area because male and female differences in sexual selection strategies for example are quite simplistic. How can they explain mate choice by females who never want children? Furthermore, the lack of archaeological evidence for how our ancestors lived their daily lives means that ancestral behaviour has to be viewed in the context of modern behaviour. Moreover, naturally we cannot know for certain what modifications over evolutionary time have been made to our genetic makeup and therefore the evolutionary approach to explaining behaviour has many difficulties in terms of its methodology.

In this chapter, animal research has been included in a number of sections in order to illustrate to some extent how far such research is fundamental to investigating the biological foundation of human behaviour. Given that some psychologists studying within the biological approach view the human as just another type of animal, sharing a similar, and similarly inherited, biological makeup, human behaviour can be understood by conducting studies on non-human animals and generalizing the results to humans. Charles Darwin also argued that the physiological makeup of different species was similar enough to warrant animals and humans being considered as comparable with each other.

Mammals such as rats, mice and non-human primates are particularly useful in psychology research because humans are also mammals hence our anatomy and physiology are comparable to these animals. For example, monkeys’ and apes’ brain activity can give an insight into human brain activity and behaviour given the similarities in structure and function. The different areas of animals’ brains are presumed to have the same function as human brains, and neurotransmitters in animals’ brains are presumed to have the same action in human brains. Rat behaviour is particularly complex and rats are strikingly similar to humans in their anatomy, physiology and genetics. With regard to mice, mice and humans share around 97.5% of their DNA. In addition, they have a short generation time and an accelerated lifespan. One mouse year, for example, equals about thirty human years. This is one reason why rats and mice are used in much animal research because effects can be observed at an accelerated rate in comparison to humans.

In clinical psychology and psychiatry, animal research has also played a major role in developing modern treatments for mental illness such as medication for illnesses like schizophrenia and depression. Using humans as the initial receivers of drugs in development would not be ethical because of the potential for physical and psychological harm, hence refining psychiatric medication on animals is seen as the only viable way of ensuring these drugs are as safe as possible. It can be seen therefore that within the fields of clinical psychology and medicine, animal-based studies have been instrumental in helping countless patients live better lives.

6.2 The value of animal models in research into the brain and human behaviour

Although the advent of sophisticated neuroimaging technology has revolutionised the study of the brain in both human and animal participants, the fact remains that this technology still cannot provide a detailed enough assessment of brain structure and physiology in comparison with invasive techniques used in animal brain research. These invasive techniques include surgical ablation and lesioning. Such procedures, as mentioned earlier, involve the deliberate removal of brain tissue (ablation) or the deliberate destruction of tissue (lesioning). The idea is that surgery of this type can be used to ascertain which brain structures are involved in different types of behaviour. The benefit of these invasive measures is that the brain can be studied in much finer detail and in a more controlled way because scientists can choose the size and location of the damage. This leads to much more precise measurements of brain function.

Martinez and Kesner (1991) conducted experimental research with rats that you read about in Section 3.4 on neurotransmitters. Their findings that acetylcholine (ACh) acted in the hippocampus and surrounding medial temporal lobe area and was important for spatial memory led to later research in humans. Antonova et al. (2011) carried out a similar experiment on humans to see if ACh acted in exactly the same way in the human brain and found that it did. See their research in Section 2.3, as an example of a well-controlled experiment demonstrating cause and effect.

Some of the human research was focused on diseases characterised by a loss of memory, such as Alzheimer’s disease. It was discovered that loss of ACh activity in the medial temporal lobe and hippocampus was one of the very early signs of Alzheimer’s disease. Drugs targeting the production of ACh in the brain have been developed for the treatment of Alzheimer’s disease. Therefore, discovering how neurotransmitters act in animal brains can lead to later clinical research on humans that can improve lives.

6.3 The value of animal models in research into hormones and/or pheromones.

Psychologists who are interested in understanding the role that hormones and/or pheromones play in shaping human behaviour rely on several types of research approaches. These would include animal research where hormone levels are experimentally altered, such as injecting mice with testosterone to measure levels of aggression or dominance. Hormones work in the same way in non-human mammals as they do in humans and therefore animal experiments with well controlled variables can isolate the effect of a hormone. The hormone insulin, which is used to treat diabetes, was discovered in an animal experiment. Testosterone seems to have a protective effect against depression. We read earlier that more women than men suffer from major depressive disorder (MDD). The study below investigates this further, using rats.

Focus on research – testosterone – Albert et al. (1986)

Albert et al. (1986) investigated the effect of testosterone on aggression in male rats. They placed the rats in cages and identified the alpha males (dominant males) by their size and strength. They measured their aggression levels when there was a nonaggressive rat placed in the same cage, by measuring behaviour, such as attacking and biting.

They then divided the alpha male rats randomly into four groups to undergo four separate surgeries:

1. Castration 2. Castration followed by implanting of empty tubes 3. Castration followed by implanting of tubes with testosterone 4. A “sham” castration followed by implanting of empty tubes (They cut open the rat and sewed it back up without actually removing the testicles).

They then measured the change in aggression when non-aggressive rats were reintroduced to the cage. Those that had the operations that reduced testosterone levels (Groups 1 and 2) had a decrease in aggressiveness but those that had the operations that kept testosterone levels intact (Groups 3 and 4) didn’t have a significant change in aggression levels.

Then the rats in Group 2 had their testosterone replaced and they showed returned levels of aggressiveness similar to those in Groups 3 and 4.

Moreover, the researchers observed that when a non-aggressive male is placed in the same cage as a castrated alpha rat then he becomes the dominant rat in the cage. Also, when a rat that had the sham operation is put in a cage with a castrated rat, the sham operation rat shows higher levels of aggression. This suggests that testosterone may facilitate behaviour associated with social dominance in rats. By experimenting on rats, Albert et al. were able to manipulate levels of testosterone and conclude that levels of testosterone affect aggression and dominance.

This study is a pre-cursor to investigations into human males and the effects of testosterone on behaviour. Of course, researchers cannot castrate human males to test the hypothesis that reduced testosterone levels correlate with reduced aggression, but they can increase testosterone levels and see if that results in increased aggression or dominance. Because of socialization, aggression or dominance in humans is not usually expressed by attacking or biting, but it is nonetheless measurable through competitive games, as in Carré et al.’s research (Section 4.1) Note that Carré et al. found that it was only when testosterone interacted with already present traits of high dominance and low impulse control that it resulted in aggression. Nave et al. (Section 4.1) found that testosterone reduced cognitive reflection, which is linked to impulse control. How might this link to Albert et al.’s selection of alpha males for their experiment?

Animal and human research into the effects of testosterone on male behaviour has also shown a reduction in this hormone to be linked to depression (Carrier and Kabbaj, 2012). It is helpful to see how animal studies can lead to human studies that test the hypotheses generated.

While there is animal research into pheromones and behaviour, none of it has been successfully generalized to humans yet, so the animal models for a hormone and behaviour remain the most useful.

6.4 The value of animal models in research into genetics and behaviour

Animal research is used to generate theory for comparable research in humans and the results of animal research are also compared with findings in humans. This is an area where there is a lot of animal research using specially bred mice. Mice share many of their genes with humans and can be bred to show specific genotypes. Also, because rodents have a much shorter lifespan that humans, differences in behaviour in response to genes is much quicker to observe. The following two studies are from earlier in this chapter, and both demonstrate gene expression in relation to environment.

Weaver et al. (2004) showed that the glucocorticoid receptor genes in the brain are methylated (switched off) when mothers neglect their baby rats (pups). This study was detailed in Section 5.1. It was a controlled experiment wherein pups were taken from their caring mothers and fostered with neglectful mothers and vice-versa, in order to identify the genetic and environmental effects of the mothers’ licking and grooming. It was found that even when pups had been born to uncaring mothers, once they were with their caring foster mother, then the glucocorticoid receptor genes were de-methylated (switched on) and their stress decreased. So this genetic response is not inherited but is a response to environment. This demonstrates epigenetics - genetic changes in response to environment.

This is similar to what was found by Suderman et al. (2014), who found that 12 adults who had suffered childhood abuse were more likely to show methylation in their DNA compared to a control group of 28 who had suffered no such abuse, even at the age of 45 years old. In particular, the study showed that there was increased methylation of the gene PM20D1 in the sample who had suffered abuse. This gene is responsible for the metabolism of amino acids and is associated with control over a person’s eating habits. Those with childhood abuse were also shown to have a greater prevalence of obesity in adulthood.

Weaver et al.’s study can show a cause and effect relationship between the licking and grooming of the pups and the demethylation of the glucocorticoid receptor genes because it is a wellcontrolled experiment. However, Suderman’s is a quasi-experiment with no random allocation to groups or control of other variables, and so can only show a correlation between the abuse, the methylation of the gene and the obesity of those who had suffered abuse as a child. This is one advantage that animal studies have over research into humans. With humans, researchers often investigate naturally-occurring events that result in biological changes in the brain and alterations in behaviour. With animals, researcher will instigate such changes in order to manipulate and control variables. This of course leads to ethical considerations. Any of the animal studies from this chapter can be used to discuss the ethical considerations of animal research.

6.5 Ethical considerations in animal research

There has been considerable debate about whether animal research should be used to further our knowledge about human behaviour. Some academics have taken a more philosophical viewpoint in this debate and discussed whether the use of animals in research is akin to concepts such as racism among humans. For example, Singer (1990) uses the term speciesism to reflect this and argues that humans and animals should be seen as equal. In addition, he believes that morally humans do not have the right to put one species’ rights before another’s. Regan (1984) agrees with this view and argues that animals should never be used in research. It can also be argued that evidence of self-awareness in animals should be a consideration against using them in psychology studies. For example, adult bonobos and chimpanzees have been shown to exhibit this ability. In one study, Gallup (1970) showed that chimpanzees could recognise themselves in a mirror, a behaviour that indicates self-awareness.

Such arguments, however, have not deflected psychology as a discipline from continuing to use animal research to explore the foundations of human behaviour. To counter ethical issues arising from such research, ethical guidelines have been developed to ensure researchers adhere to practices that minimise animal suffering. As mentioned earlier in the chapter, The American Psychological Association (APA) regularly updates its guidelines for animal research. Researchers can also use a cost-benefit analysis to weigh up the pros and cons of carrying out animal research projects. Bateson (1986), for example, proposed a decision-making tool for research called Bateson’s Cube. When researchers propose a new project with animals, Bateson outlined three factors as being important in the decision-making process. These are:

the degree of suffering by an animal

the quality of the proposed study

medical benefits of the study

As written earlier, the APA and BPS have issued regularly-updated guidelines regarding animal research and in the UK, a government licence is needed to carry out animal research. The BPS has identified the ‘3 Rs’ of animal research. These are to:

Replace animals with other alternatives - such as stem-cell research or computer modelling

Reduce the number of individual animals used (and where possible use single-cell amoebae, fruit flies or nematode worms rather than mammals)

Refine procedures to minimise suffering - ensuring all animals are well looked after

Ethical considerations should also consider whether animals could be used in natural circumstances as well as, or maybe instead of, in experiments. Observations of primates in their natural habitats, and of the effects of changing environment and family disruption on the treatment of young animals may yield richer data gained more ethically than data gained from lab studies in highly artificial circumstances. Xu et al. (2015) argued that using lab rats and mice in experiments to investigate depression that occurs naturally in a social context is not realistic. Instead, they used macaque monkeys in order to describe and model a naturally-occurring depressive state amongst monkeys raised in socially-stable groups at Zhongke Feeding Centre in Suzhou, China, where they are provided with environmental conditions and surroundings approximating those found in the wild. These circumstances make the research ethical to a greater extent than laboratory conditions would.

6.6 Assessment advice

Changes in grey matter induced by training

Bogdan Draganski 1 ,
Christian Gaser 2 ,
Volker Busch 1 ,
Gerhard Schuierer 3 ,
Ulrich Bogdahn 1 &
Arne May 1

Nature volume 427 , pages 311–312 ( 2004 ) Cite this article

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Newly honed juggling skills show up as a transient feature on a brain-imaging scan.

Does the structure of an adult human brain alter in response to environmental demands 1 , 2 ? Here we use whole-brain magnetic-resonance imaging to visualize learning-induced plasticity in the brains of volunteers who have learned to juggle. We find that these individuals show a transient and selective structural change in brain areas that are associated with the processing and storage of complex visual motion. This discovery of a stimulus-dependent alteration in the brain's macroscopic structure contradicts the traditionally held view that cortical plasticity is associated with functional rather than anatomical changes.

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Higher surface folding of the human premotor cortex is associated with better long-term learning capability

Individual differences in frontoparietal plasticity in humans

Associative white matter tracts selectively predict sensorimotor learning

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Department of Neurology, University of Regensburg, Regensburg, 93053, Germany

Bogdan Draganski, Volker Busch, Ulrich Bogdahn & Arne May

Department of Psychiatry, University of Jena, Jena, 07740, Germany

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DOI: 10.1038/427311a
Corpus ID: 4421248

Neuroplasticity: Changes in grey matter induced by training

Bogdan Draganski , Christian Gaser , +3 authors A. May
Published in Nature 22 January 2004

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Learning-related gray and white matter changes in humans, neurolinguistics: structural plasticity in the bilingual brain, experience-dependent structural plasticity in the adult human brain, structural brain alterations following 5 days of intervention: dynamic aspects of neuroplasticity., structural and functional neuroplasticity in human learning of spatial routes.

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Plasticity in gray and white: neuroimaging changes in brain structure during learning

Changes in gray matter induced by learning—revisited, experience-dependent structural plasticity in the adult brain: how the learning brain grows, training induces changes in white matter architecture, rapid changes in brain structure predict improvements induced by perceptual learning, 24 references, long-term in vivo imaging of experience-dependent synaptic plasticity in adult cortex, the multiple roles of visual cortical areas mt/mst in remembering the direction of visual motion., navigation-related structural change in the hippocampi of taxi drivers., neuroplasticity in old age: sustained fivefold induction of hippocampal neurogenesis by long‐term environmental enrichment, long-term dendritic spine stability in the adult cortex, automatic differentiation of anatomical patterns in the human brain: validation with studies of degenerative dementias, hypothalamic gray matter changes in narcoleptic patients, voxel-based morphometry—the methods, psychopharmacology, related papers.

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biological approach to behavior Notes

Module 1.1: Localization

What will you learn in this section

Localization of function is the idea that every behaviour is associated with a specific brain region
Brain structure a) Cortex b) Cerebellum c) Limbic system d) Brain stem.
Research supporting strict localization
Research opposing the idea of strict localization
Relativity of localization: the split-brain study

Brain structure

The nervous system is a system of neurons— cells that perform the function of communication in the body. The central nervous system consists of the spinal cord and the brain
The major parts of the human brain are the: a) cortex b) cerebellum c) limbic system d) brain stem.

The cortex is the layer of neurons with a folded surface covering the brain on the outside. It is the largest part of the human brain associated with higher-order functions such as abstract thought or voluntary action. Evolutionarily, this part of the brain developed the latest.
The cortex is divided into four sections called “lobes” . 1. The frontal lobes are associated with reasoning, planning, thinking a nd decision-making, voluntary action, complex emotions, and so on. 2. The parietal lobe is associated with movement, orientation, perception and recognition. 3. The occipital lobe is associated with visual processing. 4. The temporal lobes are associated with processing auditory information, memory and speech.
There is a deep furrow along the cortex that divides it into the left and right hemispheres. A structure of neurons that connects these two hemispheres is known as the corpus callosum

b) Cerebellum

The cerebellum (“the little brain”) got this name because it looks somewhat like the cortex: it has two hemispheres and a folded surface.
It is associated with coordination of movement and balance.

c) Limbic System

Localization

Localization is the ability to identify parts of the brain which serve certain functions.
The areas of brain which are of particular interest in terms of localization are

Hemispheric Localisation

The brain is contralateral. This means that the right hemisphere relates to the left side of the body and the left hemisphere to the right side of the body.
The right hemisphere has been found to have three key functions that have been supported experimentally: recognising emotion and faces, together with spatial functioning.
Research {Dundas el: aI., 2015} supports the idea that the right hemisphere is dominant for recognizing faces as in research it has been shown that participants process faces predominantly in the right hemisphere. It has also been found that this recognition of faces is more strongly associated with the right hemisphere when the recognition is of very familiar faces [Bombari et al.2014}.
However it should be noted that the brain becomes less lateralized with age with the non: dominant hemisphere supporting the superior hemisphere for any given task. This is called the HAROLD model {Hemispheric Asymmetry Reduction in Older Adults}. Therefore, in an experimental procedure it is important to consider the age of participants.

Motor centers

The motor centers of the brain are concerned with movement. There are more simple movements like reflexes, coughing, gagging, sneezing, and so on: but the more complex movements we use are coordinated within the motor cortex, which can be found in the parietal lobe of the brain.
Much of the motor cortex is actually concerned with small areas of the body such as the lips, tongue and hands, as these are areas that require fine motor movements to be performed.

Somatosensory cortex

The somatosensory area of the brain is focused specifically upon sensory information. It is positioned next to the motor cortex in the parietal lobe and works closely with the motor cortex more to allow the individual to move appropriately around their environment.

Visual center

The area of the brain which processes visual information is positioned in the occipital Lobe. It is called the primary visual cortex. There are actually two in the brain, one in both the left and right hemispheres. An area called Area VI within the primary visual cortex seems to be necessary for perceiving visual stimuli.
This is apparent from cases where there has been damage in that specific area.

Auditory center

There is a primary auditory cortex in both hemispheres. This is required to process complex sounds and is situated in the temporal lobe.
If there is a lesion in the area then the individual can still hear some sound, but anything that is complex like speech or music cannot be processed.
As the brain is contralateral, sounds heard by the right ear are processed predominantly by the left hemisphere and vice versa. However, unlike the motor cortex, there is not a clearly defined split as some sounds from the right car are processed on the right side of the brain too.

Language centers

Our production and processing of language occur in many areas across the brain, depending on the function required and modality.r (ie. sound, written, oral production )of the language. This section considers two areas: Broca’s and Wernicke’s areas.

a) Broca’s area

The function of Broca’s area is speech production and it is situated in the frontal lobe very close to the temporal lobe, in the dominant hemisphere.
Ninety-six per cent of right handers and about 75 percent of left handers have the left hemisphere as their dominant hemisphere for language.
Individuals with a lesion in this area cannot produce speech, but their understanding and processing of other aspects of language remain unimpaired.

b) Wernicke’s area

Wernicke’s area is key to understanding language and, more specifically, speech. This area is close to the auditory cortex and can he found where the temporal and parietal lobes meet in the dominant hemisphere for language {which is usually the left hemisphere}
It is linked to Broca’s area, as the two are closely related, with a bundle of connecting neurons called the arcuate fasciculus.
Interestingly Wernicke’s area is also found in deaf people who use sign language which suggests that its purpose is for more than just speech.

Research restricting the idea of strict localization

Karl Lashley (1890–1958) used the technique of measuring behavior before and after a specific seriously controlled induced brain damage the the rats’s cortex. In a typical study he would prepare the rat to run out a maze without errors in search of food. After learning occurred, he would remove an area from the cortex.
The principle of mass action based on a similarity observed between the percentage of cortex removed and the learning abilities. The lesser the cortex, the slower and more inefficient learning.. The main aim here is deterioration in performance depending on the cortex’s percentage destroyed but not in the area of the cells which are destroyed.
Equipotentiality —This describes the capacity of one region of the cortex to adopt the functions of another.
These observations led Lashley to conclude that memory is widely distributed across the cortex. This conclusion is mostly held up today. However, it has been proven that memory is not as same (and However, it has been shown that memory is not as evenly ( and similarly) distributed in the cortex as what Lashley expected.
To some extent the difference in the two extreme positions (the localizationism of Broca, Wernicke and Pen eld versus the holism of Lashley) may be explained by the methods they used in their studies. Aphasia was being relied on by localisationists leading to brain damage. Holists looked into maze running behavior. However, learning to run through a maze is in itself a highly complex behavior that involves motor and sensory functions, so it may not be suitable enough for the study of localization.
There needs to be a converging position that is a more accurate rejection of localization in the brain. Currently,: localization is supported by neuroscience by admitting localization for some functions under certain conditions, but it outlines the limits of localization clearly.
Before we formulate these limits let’s look at another research study that demonstrates relativity of localization of function (that is, localization and distribution at the same time): split-brain research by Gazzaniga (1967) and Sperry (1968).

Relativity of localization: the split-brain research

It has to be noted that split-brain studies represent research into lateralization—the division of functions between the two hemispheres of the cortex. Lateralization is a special case of localization.
Research in this area was pioneered by Roger Sperry. Initially, the studies were conducted with animals, for example, cats.
An opportunity to replicate the studies with humans emerged when it was discovered that surgically cutting corpus callosum was an effective measure against severe epilepsy with uncontrollable seizures. Roger Sperry was joined by Michael Gazzaniga, and in 1967 Gazzaniga published results of the research with human split-brain patients. Four of the ten patients who had undergone this surgical procedure by that time agreed to participate. The patients were examined thoroughly over a long time period with various tests.
The aims of the study were to test the theory of lateralization and to see if the two hemispheres have uniquely different functions.
Initial observations showed that patients seemed to be remarkably unaffected by the surgery. There was no change in their personality and intelligence, and one of the patients on awakening from the surgery joked that he had a “splitting headache” and recited a tongue-twister.
The authors devised a technique where the participant had to sit in front of a board and look at the dot in the middle of it. Visual stimuli would then be presented for one tenth of a second either to the left or the right visual eld (the far left or far right on the board). Optic nerves from the left eye are connected in our brain to the right hemisphere, and vice versa. So, by presenting the stimulus to the left visual field the researcher “sends it” to the right hemisphere, and stimuli from the right visual field goes to the left hemisphere. Also, a variety of objects were placed behind the screen so that participants could feel them with their hands.

Module 1.2: Neuroplasticity

Neuroplasticity is the ability of the brain to change through the making and breaking of synaptic connections between neurons; causing factors are both genetic and environmental
Different scales of neuroplasticity—from synaptic plasticity to cortical remapping
Merzenich et al (1984): cortical remapping of sensory inputs from the hand occurs within 62 days in owl monkeys— adjacent areas spread and occupy parts of the now unused area for the amputated digit
Example 1—Draganski et al (2004): learning a simple juggling routine increases the volume of grey matter in the mid- temporal area in both hemispheres; lack of practice makes this area shrink, but not to the original size
Example 2—Draganski et al (2006): learning large amounts of abstract material leads to an increase of grey matter in the parietal cortex and the posterior hippocampus

Definitions

Neuroplasticity is the ability of the brain to change throughout the course of life. When the synaptic connections are made and broken a change occurs between the neurons. In this process neural networks in the brain literally change their shape.
Genetics(generally pre programmed development of the brain) and environmental (for eg: injury or damage in the brain or simply learning new skills) are responsible.
Neuroplasticity can be observed on different scales. a) On the smallest scale, at the level of a single neuron, it takes the form of synaptic plasticity: the capability of the neuron to generate new synaptic connections and break the old ones b) On the largest scale, neuroplasticity takes the form of cortical remapping: the occurrence of the brain area X assumes brain area Y’s function for example, due to injury.
Synaptic plasticity depends on the activity of neurons. If two close-by neurons are oftenly activated at the same time; a synaptic connection between the two neurons may slowly form. Likewise if two neurons are hardly activated together the functioning connection may slowly fall apart. This has been summarized like this: “neurons that are together, wire together” (which was originally said by Carla Shatz and is quoted in Doidge, 2007) and “neurons that are out of sync, fail to link” (Doidge, 2007, pp 63–64).

Remapping of the sensory cortex

One of the early studies of neuroplasticity on the level of cortical remapping was done by Merzenich et al (1984). Researchers studied the cortical representation of the hand in eight adult owl monkeys. The procedure involved three steps.

Results of the first mapping showed that there were five distinct areas in the brain, each responsible for one finger, and adjacent fingers were represented in adjacent areas in the cortex. It was found that the adjoining area (the ones responsible for sensitivity from digits 2 and 4) spread and occupied parts of the area which is unused. The areas responsible for digits 2 and 4 became larger while the areas responsible for digits 1 and 5 stayed the same. It was concluded that cortical remapping of sensory inputs from the hand occurs within 62 days in owl monkeys.

Neuroplasticity as a mechanism of learning

Example 1—Draganski et al (2004): learning a simple juggling routine increases the volume of gray matter in the mid- temporal area in both hemispheres; lack of practice makes this area shrink, but not to the original size.

The researchers used a random sampling design and a self-selected sample—they randomly allocated a sample of volunteers into one of two groups: jugglers and non-jugglers
No difference was shown in the brain structure in the scans of the two groups before the start of the experiment
At the second scan, however, more gray matter was seen in some areas of the cortex of the juggler group , the mid temporal in both the hemispheres. These areas were known to be implicated in coordination of movement.
These differences got smaller on the third scan, but there was still more gray matter in these areas in jugglers than there was on the first scan. Also, a correlation was seen between the performance of the juggling and amount of change brain changes in participant When you fail to practice, they shrink back significantly (perhaps not to the initial state, though)

Example 2 — Draganski et al (2006):increasing the amount of gray matter in the parietal cortex and posterior hippocampus by studying a lot of abstract material.

Draganski et al (2006) glanced at 12 subjects of control and about 38 students studying medical matched for the age and gender. 1. The first scan was obtained three months before the examination, 2. The second scan on the first or second day after the examination, and 3. The third scan three months later (after the examination the students had a break).
Results showed that, although there were no differences in regional gray matter at baseline, there were two major changes occurring in the brains of the medical students. a) The gray matter was increased in the parietal cortex in both the hemispheres respectively. By the time of the third scan The volume of gray matter in this region did not reduce. Studying for an examination in medicine has a more lasting impact on the brain. The changes stay with you even after a study break. b) The gray matter in the posterior hippocampus grew. The pattern was different here. The gray matter was slowly increased comparative to the first scan in the third. That is, gray matter in the hippocampus continued to grow even after the examination. c) Stress is known to reduce gray matter volume in hippocampal regions. This may have resulted in two opposite effects on the hippocampus simultaneously between the first and the second scan: learning increased gray matter in the posterior hippocampus but examination stress decreased it. After the examination this negative influence of the examination stress was corrected and the lost hippocampal volume was restored, while the gray matter that was formed due to learning remained

Module 1.3: Neurotransmitters

The structure of a neuron

Electrical processes: threshold of excitation, action potential
Chemical processes: neurotransmitters and how they function
Excitatory and inhibitory neurotransmitters
Agonists and antagonists

Limitations in neurotransmitter research

Effect of serotonin on prosocial behaviour Serotonin reduces acceptability of personal harm and in this way promotes prosocial behaviour Crockett et al (2010)—participants solved moral dilemmas after receiving a dose of either citalopram (an SSRI) or placebo
The role of serotonin in depression The serotonin hypothesis: low levels of serotonin in the brain play a causal role in developing depression
Effect of dopamine on romantic love Fisher, Aron and Brown (2005): looking at pictures of loved ones is associated with higher activity in the dopaminergic pathway—a system that generates and transmits dopamine and increases dopamine-related activity in the brain
The role of dopamine in Parkinson’s disease Freed et al (2001): transplantation of dopamine-producing neurons in the putamen of patients with severe Parkinson’s disease results in some clinical benefit in younger but not older patients

Nervous system processes

the body (soma),
dendrites and
Dendrites and axon are filaments that extrude from the soma: typically multiple dendrites but always a single axon. Dendrites and soma are responsible for receiving signals from other neurons,
where as axons are responsible for further transmitting signals. Where the axon of one neuron approaches a dendrite or soma of another neuron, a synapse is formed. This means that a synapse (or a synaptic gap) is a structure that connects two neurons: the word “synapse” comes from the Greek synapsis meaning “conjunction”.

Electrical ( threshold of excitation, action potential) and Chemical processes (neurotransmitters and how they function)

The nature of information transmission in the nervous system is partly electrical and partly chemical.
Every neuron has a certain threshold of excitation received from the other neurons, and if the sum excitation exceeds this threshold, the neuron “fires”—generates a brief pulse called action potential that travels with the axon to the remaining neurons, passing the excitation further.

The pulse reaches the end of the axon and there, the transmission of the mechanism becomes chemical at the gap of synaptic.
When the action potential stretches to the very end of the axon, neurotransmitter is let out from the terminal of the axon into the gap of synaptic.
Neurotransmitters are chemical messengers. They are constantly synthesized in the neuron and moved to the axon terminal to be stored there. For a short period of time in the gap of synaptic a let out neurotransmitter is available whilst it may be destroyed (metabolized), and made to return into the pre synaptic axon terminal by reuptake or reach the post- synaptic membrane and bind to one of the receptors on its surface.
If the neurotransmitter binds to a receptor in the postsynaptic membrane, this process makes a difference in the membrane potential and so it provides aid in activating an electric pulse in the postsynaptic neuron. Here the chemical mechanism becomes electrical again.

Neurotransmitters

Excitatory :- To cross the synapse, excitatory neurotransmitters grant permission. The brain is stimulated by their effects.
Inhibitory:- The impulse is halted by inhibitory neurotransmitters, which prevent it from traveling through the synapse. The brain is calmed by their effects.-
These neurotransmitters are always in a state of dynamic balance. When excitatory or inhibitory neurotransmitters are not within the optimal ranges in the brain it may lead to various behavioral malfunctions such as mental disorders.

Agonists and Antagonists

Agonists :Agonists are synthetic compounds that upgrade the activity of a synapse-
Antagonists:- Chemicals called antagonists work against a neurotransmitter to prevent the signal from being transmitted ahead.
Many drugs function as agonists or antagonists. For example, a class of drugs known as SSRIs (selective serotonin reuptake inhibitors) selectively inhibit (block) the reuptake of the neurotransmitter serotonin from the synaptic gap. This increases the concentration of serotonin in the synapse. SSRIs have been shown to be effective against depression.
As you see, neurotransmission is a complex process determined simultaneously by multiple factors.
X may function as an agonist for neurotransmitter Y, which in turn may affect behaviour Z. In other words, the effects of neurotransmitters may be indirect,
X may serve as a trigger for a long-lasting process of change in a system of interconnected variables. In other words, the effects of X on Z may be postponed.
X is usually not the only factor affecting Z.
X is never the only factor that changes. As you artificially increase the level of X, this may result in various side effects.
Research into the influence of neurotransmission on behavior will therefore always be reductionist in the sense that we need to manipulate one variable (X) and assume that it is the only variable that changes.
Serotonin is an inhibitory neurotransmitter that is involved in sustaining stable mood and regulating sleep cycles, for instance.
It is found in the gastrointestinal tract as well as the brain and is implicated in mood regulation.
Changes in the levels within the brain are evident when an individual is experiencing an elevated mood and lower levels are observed when there is a depressed mood.
The recreational drug ecstasy raises levels of serotonin and its ameliorating effect on mood is well researched. Low levels of serotonin are associated with depression and SSRls {selective serotonin uptake inhibitors}. which are antidepressants that raise the levels of serotonin within the brain and help some patients suffering from depression.
Another potential effect of serotonin levels on behavior is aggression. Increased levels of aggression when serotonin levels are lower have been found in humans This is thought to occur through the serotonin levels affecting emotion processing in the brain.
Dopaminergic pathway is a system that generates and transmits dopamine and increases dopamine-related activity in the brain. It is a reward system because dopaminergic activity is associated with motivation and feelings of pleasure.

Role of Dopamine in Parkison’s disease

Parkinson’s disease is a degenerative disorder that mainly affects the motor functions of the nervous system. The early symptoms of the disease are shaking, rigidity, and difficulty with movement and walking. Later in the development of the disease, thinking and behavioral problems also occur. For now Parkinson’s disease doesn’t have a cure and the exact causes are unknown
The dopamine hypothesis focuses on the idea that low levels of dopamine in the system of an
individuals are linked to the onset of parkinson’s while high levels of dopamine in the system of an individual are linked to the onset of schizophrenia. High levels of dopamine appear to increase the activity within the neurons, which means the level of communication is also increased.

Module 1.4: Hormones and Pheromones

Difference between hormones and neurotransmitters

The function of hormones
Examples of hormones
Examples of phermones

Hormones are released into the bloodstream and travel with blood to reach their destination. Conversely, with the nervous cells neurotransmission is the communication. Because of this the hormones cover the areas where the nervous system cannot, as the blood vessels network is more elaborated The nervous system supervises relatively fast process (movement, emotion, decisions, and so on), whereas hormones are able to regulate the enduring ongoing processes like metabolism , growth, reproduction and digestion.
Normally, the voluntary control over neural regulation is higher comparative to the hormonal regulation. For example, it is possible for you to control your emotions to a certain extent, whereas the degree of control you have over your growth is negligible.
However, it should be noted that the nervous system and the endocrine system are interdependent. These two systems interact and to some extent can influence each other. Also, some chemicals at times could be both neurotransmitters and hormones for example, adrenaline.
Hormones are released by endocrine glands: adrenal glands, hypothalamus, pineal gland, pituitary gland, thyroid, parathyroid, thymus, pancreas, testes and ovaries. Together, these form the endocrine system.
Cells can be only influenced by hormones if they have the receptors of the hormone respectively. These cells are known as target cells. When a particular hormone ties to a receptor it releases a sequence of changes, and in that some of them are genomic, meaning gene activation or gene suppression. Most importantly this means that the hormones do not have an influence on the behavior directly. Instead, they take a turn to the probability that a particular behavior is bound to occur in response to a particular environmental stimulus. This is like buying ice-cream on a hot day: hot weather itself does not cause you to buy ice-cream, but it certainly increases the probability that you will.
There are a variety of hormones produced in the body and they all have different functions. The most well-known hormones include adrenaline, noradrenaline, cortisol, oxytocin, insulin, testosterone and estrogen.

1. Oxy-tocin

It is mainly produced and released in the blood that is the pituitary gland. hypothalamus and released into the blood by the pituitary gland. It plays a vital role in the process of sex reproduction , childbirth and social bonding of a human being. It has been referred to as “the love hormone”, “the bonding hormone” and “the cuddle chemical”. During wet nursing, for instance, stimulation of the nipple releases oxytocin, which helps to improve the relationship between the mother and her child. A person also releases oxytocin when they hug or kiss another person.

2. Testosterone

Testosterone is an androgen: a male hormone. It is not found exclusively in males but generally the amount found in females is much lower than that found in the male population.
Testosterone is often linked to aggression and research has shown a link between the hormone and aggressive behavior. However, this appears to be predominantly in non-human animals.
In humans, the relationship is more complex1 with testosterone not being implicated in all aggression, but mainly aggressive reactions to social provocation
It is also implicated in behavior classified as masculine, as it is an androgen.

3. Adrenaline

The heightened state brought about by an adrenaline increase is well-known. The term ‘adrenaline rush’ is widely used for the feeling that an arousing situation can bring about, and the description ‘adrenaline junkie’ is used to describe someone who actively seeks an adrenaline rush.
Adrenaline is secreted by the adrenal glands located on top of each kidney. When an individual perceives a threat or potentially stressful situation, adrenaline rushes through the system triggering a racing heart and tense muscles, along with other effects.
All these are part of the flight response. The term fight or flight’ is used to describe the circumstances under which adrenaline is released into the body; this response will probably save everybody’s life at some point. It is designed to allow the body to deal with threat and danger.
While encountering the battle or a flight reaction, an individual can move quicker [due to the strained muscles] and take in more oxygen {due to the respiratory changes}. This enables a rapid exit from the stressful situation, or indeed the ability to fight. The raised heartbeat helps to send the adrenaline around the system and gets blood to the muscles and organs. This means that a relationship between the physiological and behavioral reaction to situations and adrenaline is likely.
High levels of both adrenaline and testosterone have been found in a personality type called ‘sensation seeking’. People who are sensation seekers are able to cope with and like high levels of stimulation in the environment because they like their body to be in a heightened state of arousal such as riding roller coasters, parachuting and car racing .

The word pheromone is derived from a Greek word “phero” which means I carry and hormone which means stimulating, so pheromones are chemicals that “carry stimulation”.
These chemical substances that are emitted by humans and nonhuman animals into their environment. This can occur in several ways, but the most frequent release of pheromones is in the sweat of the individual. These chemical substances are thought to elicit an effect on the environment itself and other animals in the environment.
In non-human animals pheromones are a method of communication. Transmission occurs via sweat and other €• fluids such as urine. Humans are also thought to be affected by pheromones. Those argued to elicit a specific behavioral effect are called releaser pheromones and in certain contexts or situations, they trigger specific behavior. In other situations, the same pheromone may act as more of a primer.
An example of the distinction between these two studies’ effects is found in the pheromones in male mouse urine. The releaser effect role is to make a person’s behavior more aggressive when a meddler is perceived. Menstrual synchrony is also promoted by the pheromone in the female mice.

Localization of processing pheromonal information in the brain

Pheromonal information in animals’ brains is not processed in the same brain regions as ordinary smells, despite the fact that many of the pheromones can smell. The main olfactory bulb refers to the part of the brain that processes smell. Pheromones, on the other hand, are processed in a different way than other smells.
The vomeronasal organ (VNO) is a separate structure found in mammals’ anterior nasal cavities. In the brains of animals, nerves from the VNO connect to the accessory olfactory bulb. According to Hertz (2009), this area is separate from the main olfactory bulb but adjacent to it.
Due to the fact that humans lack either the VNO or the accessory olfactory bulb, it can be challenging to extrapolate animal research to human behavior. However, we need to be accurate on this point: The accessory olfactory bulb is present in human fetuses, but it regresses and disappears after birth. The VNO is present in some people, while others do not. Even in individuals who have the VNO, it appears to be inoperable: There is no connection to the brain or spinal cord. If the human brain actually processes pheromonal information, it must be processed elsewhere.

Research into attraction

Pheromones are implicated in attraction in both humans and nonhuman animals. There are specific pheromones secreted that arouse and encourage sexual activity in males and females. In the animal kingdom. The boar pheromone is secreted via the male boar’s saliva when he is sexually aroused and this transfers to the air. The sow will detect the pheromone nasally and assume a standing position that makes it possible for the boat to mount
In humans, there is thought to be an effect from secretion of a steroidal compound found in male sweat called androstenedione. It is found in women too, in lower levels. They found that the literature indicates that exposure to androstenedione does indeed increase attractiveness in mates, improves mood and also increases sexual amuse and desire.

Research into menstrual effects

Stern and Me Clintoelr. [1998) found that when women received ‘odorless compounds from women’s armpits in the latter half of their menstrual cycle, their menstrual cycle was shortened, presumably by the effect of the other women’s pheromones as they approached the end of their cycle.
The compounds were transferred hv the women wiping a pad, which had previously been wiped across the donor’s armpit, above their upper lip.
However, if the compounds {which included pheromones } were collected from women at the beginning of their cycle, this had the opposite effect, lengthening the cycle of those who had received the compound. This shows that the menstrual cycle of a woman can be altered by communication via pheromones. This is a priming effect.

Module 1.5: Genes and behavior; genetic similarities

Genotype and Phenotype

Genetic similarities: twin study, the influence of genetics on the environment.

Aggression and genetics

Anxiety and genetics

All cells in the human body that have a nucleus contain a set of chromosomes .
A chromosome is a thread-like structure that contains a DNA molecule. The long DNA molecule is tightly coiled many times around supporting proteins, so a chromosome is a “package” that contains folded DNA.
DNA (deoxyribonucleic acid) stores information. It is a code made up of a long sequence of four chemical bases (A = adenine, G = guanine, C = cytosine, T = thymine). The bases are paired up, making a sequence of base pairs.
The DNA has a characteristic structure of the double helix which looks a bit like a ladder where base pairs are the ladder’s rungs (US National Library of Medicine, 2017). Information is coded in this sequence of bases like letters in a sentence (change the order of letters and you get a different sentence).
The long sequence of chemical bases is broken up into 23 chromosomes, so each chromosome contains a part of the sequence. Each chromosome is present twice in each cell (except for sex cells).
Humans have 23 pairs of chromosomes. One of the chromosomes in Each pair is from your mother and the other one from your father. Both the chromosomes in the pair have a code for identical characteristics (height, eye color, and so on), but the chromosomes themselves might not be identical.

If DNA is one extremely long sentence, and base pairs are letters, then genes are probably words. A gene is a unit of heredity, a region of DNA that encodes a specific trait or function.
For example, there is a gene for eye color, a gene for height, and so on. The total number of genes in the human organism is currently estimated to be around 20,000.
Alleles are different forms of the gene. They can be dominant or recessive. The trait controlled by the recessive allele only develops if the allele is present in both chromosomes in the pair, whereas the trait controlled by the dominant allele will develop if at least one of the chromosomes in the pair contains it.
For example, in the gene that codes for eye color the allele for brown eyes is dominant and the allele for blue eyes is recessive. So you will have blue eyes only if both the alleles in your chromosome pair are recessive.
The set of traits as coded in an individual’s DNA is called genotype. The set of traits that actually manifest in an individual’s body, appearance or behavior is called phenotype.
Phenotype comprises observable characteristics (eye color, height, and so on) and unobservable characteristics (blood type, immune system, and so on), as well as behavior.
Genotype is the “plan” and phenotype is its implementation.

The Nature –Nurture Debate

Nature-nurture is the long-lasting debate in psychology and philosophy that attempts to establish whether human behavior is determined primarily by biological factors such as genetics and brain structure (that is, nature) or environmental factors such as education and friends (that is, nurture).

One of the key ways that genetic research can be conducted is by using twin studies. By using twin pairings, the level of heritability for any given behavior can, in theory, be calculated due to the genetic relatedness of the individuals.
There is a core assumption that underpins this type of methodology. As identical {monozygotic or M2} twins come from the same fertilized egg, they are 100 per cent genetically similar and non-identical i{dizygotic or DZ} twins share half their genes, as they come from different fertilized eggs, so any differences in behavior should be attributable to how similar the twin’s genetics are.
This works on the assumption that the environment is the same for both twins {i.e. shared womb and home environment}. For example, if all the identical twins demonstrate a behavior and only half of the non-identical twins do so, then there is the suggestion that genetics can explain the behavior. In the real world, this rarely happens and concordance rates are used to ascertain the level of heritability.

If identical twins have a concordance rate of 30 per cent for a behavior and non-identical twins have a 32 per cent concordance rate for the same behavior, the difference between the two concordance rates can be attributed to the differences between the two types of twins (M2 or D2} in terms of genetic similarity.
However, it can also be said from the concordance rates that there are environmental influences because otherwise the concordance rate for identical twins would be 100 percent.
Family studies are also conducted to examine behavior and its heritability level. By looking through a family tree and looking at members who may be diagnosed with a condition geneticists have estimated heritability of that condition.
Genes and environment are not completely independent: in many instances genes influence the environment too.
One form of this dynamic development is niche-picking: the situation in which a person’s genetic predisposition causes them to choose environments that start to affect their behavior. For example, a child who is likely to be open to depression may deliberately seek high demanding environments where it is genuinely not easy to succeed. Niche-picking may explain one interesting property of heritability coefficients: they change during life, typically becoming larger. This means that if you use a sample of adolescent twins and the Falconer model to arrive at an estimate of heritability (A), this estimate will typically be smaller than if you use a sample of older twins. As you grow up, your genetic programme “unfolds’ ‘ causing you to choose certain “niches’ ‘ in the environment. In this way, in terms of their behavior, MZ twins become more and more similar with age.
Adoption studies provide a direct test of environmental malleability of cognitive abilities. There are two aspects of adoption studies that may provide slightly different angles on the nature nurture problem. These aspects are: a) computing the correlation between cognitive abilities of the adopted child and the adoptive parents and comparing it to the correlation between cognitive abilities of the adopted child and the biological parents b) comparing cognitive abilities of adopted children to those of their siblings who were not adopted but raised by their biological parents.

Aggression and Genetics

The link between testosterone and aggression was discussed briefly in the previous section, It is also entirely possible that the high levels of testosterone implicated in aggression are a consequence of the individual’s genetic code.
if this is indeed the case then it would be expected that the higher levels of testosterone would also be evident in the individual’s relatives. Other bio-chemicals such as serotonin. dopamine and adrenaline are implicated too.
Genes can affect testosterone levels, as they have an effect on the way that the hormone is metabolized {this is the word used when a biochemical is processed by the body}.
In terms of brain physiology, the frontal lobe is known to have properties that exert control and therefore some individuals’ brain physiology will mean that the control element is not as strong, leading to aggression.
This frontal lobe physiology could be genetically determined. However, merely demonstrating how the genes could prompt changes to the ph biology and biochemical make-up of an individual is not sufficient; there needs to be an identifiable gene, or series of genes, if the genetic link to behavior can be made.
Anxiety is a feeling of apprehension and worry. For many sufferers of anxiety disorders , anxiety is not enabling in any way, indeed it means that life can be difficult as the individual is held back by their anxiety.
Evolutionary psychologists argue, however, that anxiety is evolutionarily adaptive. It prevents the person who is experiencing the anxiety from potentially putting themselves in danger, which increases their chances of survival.
The problem comes when the anxiety levels become too high and are not adaptive. Nesse & Williams (1995) called the anxiety regulation mechanism the ‘smoke detector principle’.
They argue that it is an evolutionary adaptation to have a heightened awareness of potential threats and that manifests itself as anxiety. However, Like a smoke detector, it is set to be triggered at the smallest sign of threat and, like the smoke detector, it is necessary for us to be aware of problems.

Module 1.6: Techniques used to study the brain in relation to behavior

Computerized axial tomography (CAT)
Magnetic resonance imaging (MRI)
Functional magnetic resonance imaging (fRMI)
Positron emission tomography (PET)
Electroencephalography (EEG)
There are a variety of techniques used currently to investigate relationships between the brain and behavior, they are collectively known as brain imaging techniques, or neuroimaging. These brain imaging techniques use varying ways to collect the information on brain structure and activation
computerized axial tomography (CAT)
positron emission tomography (PET)
magnetic resonance imaging (MRI)
functional magnetic resonance imaging (fMRI)
electroencephalography (EEG).

a) Computerized Axial Tomography (CAT)

Computerized axial tomography (CAT) works on the principle of differential absorption of X-rays. The object is on the table that slides inside a cylindrical apparatus, one-half of the cylinder projects X-rays across the cylinder to the other side, traveling through the brain. The other side of the cylinder has a detection unit to detect the X-rays. Using this movement across the front of one side of the cylinder to the other, many still photos can be taken as the cylinder rotates around the head. When all the images are merged they form a 3-D picture of the physiology of the brain.
Bone and hard tissue absorb X-rays better than soft tissue. As multiple X-ray beams go through the head it is possible to expose the brain’s structural features.
The strength of this technique is that it is a quick non-invasive method of studying brain structure. It has an advantage over standard X-rays because CAT records images of hard and soft tissue as well as blood vessels simultaneously.
Unlike the other techniques present , CAT scans are available to people who have medical devices implanted in themselves.
The CAT scan leads to some amount of radiation exposure.

b) Positron Emission Tomography (PET)

Positron emission tomography (PET), like fMRI, uses blood flow as the indicator of brain activity.
A radioactive tracer is used to bind itself to molecules naturally used in the brain, fluorodeoxyglucose {a form of glucose}. This is done into the carotid artery in the neck.. This radioactive tracer is administered into the subject’s blood stream. It has a short period of time (that is, it decays quickly). The frequencies of the radio frequencies emitted by the decaying tracer are registered by the scanner. Brain areas that are more active require more blood supply, so the distribution of the tracer in the brain will depend on what regions are mostly in use at the time of the scan.
PET has a decent spatial resolution of about 4 mm throughout the brain. However, its temporal resolution is only 30–40 seconds, so quick processes are not easily detected.
The biggest advantage of PET scans is their good spatial resolution
They are used less and less these days given the existence of non- invasive alternatives (fMRI) which do not require administration of a radioactive chemical.
PET is useful for detecting tumors and metastases, as well as other diffuse brain diseases, so that it becomes clear what areas are affected by the spreading disease. It is often helpful in diagnosing causes of dementia.
Another advantage of PET is that scanners can be small—so small that a small PET scanner has been constructed that can be worn by a rat on its head like a hat. The device is called RatCAP (Schulz et al, 2011). The rat is conscious and fully mobile, it performs various tasks while its brain activity is being measured. This is very useful for research and potentially can lead to a lot of insights into brain functioning.

c) Magnetic Resonance Imaging (MRI)

MRI’S main principle is the atomic nuclei —in particular those of hydrogen atoms— are able to emit the energy when it’s placed in an external magnetic field. When the scanner detects the pulses of the energy, the relative distribution of hydrogen atoms in the brain can be mapped easily. Hydrogen atoms exist naturally in the body, but their concentration in different types of tissue is different. For example, the highest concentration of hydrogen atoms is found in water (H2O) and fat. Analyzing the pattern of emission of energy in response to magnetic fields, we can see inside the brain.
After excitation by the magnetic field each tissue returns to its equilibrium state—and the time required to do so differs in different types of tissue. This information is also analyzed. This is why it is necessary to rapidly change the parameters of the magnetic field and switch it on and off repeatedly. The result is the loud noise that is characteristic of any MRI scanner.

The advantages of MRI as compared to CAT include the following.

It allows non-exposure to radiation and, as a consequence, less risk of radiation-induced cancer.
MRI has better resolution. This makes it particularly useful for detecting abnormalities in soft tissue—such as the brain.

The disadvantages of MRI as compared to CAT include the following.

People with metal in their body, for example, cardiac pacemakers or shrapnel, cannot undergo the procedure because metal will attract to the magnetic eld (one can only imagine what happens). Several deaths have been reported in patients with undisclosed metallic implants who underwent the procedure.
An MRI scan can be an issue for claustrophobic people because it requires being placed in a narrow tube. Also, longer scan times are required: in some cases people have to stay inside the tube for as long as 40 minutes. Specially constructed mirror glasses are sometimes used to create the illusion of openness of the space inside the scanner.
Lying still for a long time may be problematic for young children, especially since the procedure is new and may be frightening. For this reason, children having MRI scans are often sedated. Some clinics try to turn MRI scans into a fun adventure, pretending that the MRI scanner is a pirate ship, for example.
An MRI scan is more expensive than a CAT scan. However, the costs are falling.
Interestingly, the high resolution and sensitivity of an MRI scan is a risk in itself due to incidental findings. Sometimes the scan will then pick up the disturbance or abnormalities in the brain structure which might not be related to the symptoms which can be investigated. This may cause anxiety and cause patients to seek unnecessary treatment.

d) Functional Magnetic Resonance Imaging (FMRI)

Functional magnetic resonance imaging (fMRI) is called functional for a reason: A dynamic image of the scan is obtained while MRI and CAT are only able to study and show the structural features of the human brain, fMRI can also show the ongoing brain processes.
In a typical fMRI study the subject is asked to do or carry out a task on which time of the activity is altered with the time of the rest The main principle of this work is that the flow of oxygenated blood increases gradually in that region during the task is performed.. The principle at work is that The response of blood to rapidly changing magnetic fields differs depending on the flow and the level of oxygenation.
The signal that is analyzed by the fMRI scanner to reconstruct brain activity is known as BOLD (blood-oxygen-level dependent) signal. Other biomarkers also exist but amongst them BOLD is widely used. The energy used by brain cells is directly correlated with the oxygenated blood used by brain cells, and this directly corresponds to the level of the activity in a particular part of the brain..
An fMRI scan, just like any other brain imaging technique, is characterized by spatial resolution and temporal resolution.
Spatial resolution is the ability to discriminate between nearby locations: just as with the resolution of your computer screen, the lower it is, the more pixelated the picture and the less detail you can discern. Whereas resolution of your screen is measured in pixels, that of an fMRI scanner is measured in voxels. You can think of them as “volumetric pixels”—a cube of neurons. A voxel is the smallest “brain particle” that we are able to see through a scanner. Typically, The scanner is able to work with the ranges from 1 to 5 mm as the size of the voxel. Small voxels have less blood flow, so the signal is weaker and the required scanning time is longer. A voxel contains several million neurons and several billion synapses. This marks the limit of what can be achieved with brain imaging technology: we can only see a relatively crude picture of brain functioning.
Temporal resolution is the shortest time period in which the changed brain activity can be registered. Think about the rate as that the snapshots are taken—“frames per second”. Currently, the temporal resolution achieved in fMRI is about 1 second. This also marks a limitation: fMRI is well suited for studying processes that last at least for several seconds (memory, face recognition, thinking about alternatives of a choice and emotional reactions) but is not suited for studying instantaneous processes such as information traveling from the retina to the visual cortex (which takes milliseconds).
A clear scan requires the subject’s head to be motionless, but this is not realistic. Random thoughts and sensations also result in noise. A lot of noise can be accounted for if the number of trials is sufficient and powerful statistical techniques are used, but some sources of bias are impossible to eliminate.

These are the advantages of fMRI.

It proposes excellent spatial resolution (up to 1–2mm).
It grants allowance to us to go through the brain process unlike the usual brain structural imaging technologies, however

There are some disadvantages.

The resolution of temporal is poor is (about 1 second) comparatively to electromagnetic techniques such as EEG (<1 millisecond) when used.
All the same things are considered in an MRI and as well as fMRI like the cost of the machine , the claustrophobic claustrophobia, time taken for the procedure and the inability to use it with the implants of medicine.

e) Electroencephalography (EEG)

Electroencephalography (EEG) calculates electric potentials created by neural circuits. Neurons communicate with each other by sending electrical impulses along their axons.
The impulse Fired in the individual neuron is not seen to any foreign device outside the skull as the impulse is very outside of the skull because the impulse is microscopic. However, when large amounts of neurons fire simultaneously , electric potentials made by these impulses turn detectable at the main surface. Predetermined points on the scalp are inclined toward the electrodes, which detect changes in the electric potential of the scalp regions. This information is vital to generate an electroencephalogram.
EEG has a perfect temporal resolution. It is capable of detecting changes in brain activity within milliseconds. In this sense it outperforms other techniques such as fMRI. However , its spatial resolution is a weakness: in practice EEG is never used to set up in the origin of the electrical signal EEG i s good for measuring brain activity “on the whole”.
As it makes visible changes in the overall patterns of brain activity (sometimes referred to as brain waves), EEG is commonly used to diagnose such conditions as epilepsy and sleep disorders.

These are the advantages of EEG.

It is a low-cost technique.
Unlike PET and fMRI, EEG measures neuronal activity directly.
EEG can be offered as a mobile service because the apparatus can be manually transported. For comparison, the weight of an fMRI scanner is about 1 ton.
EEG is silent, which is an advantage because responses to auditory stimuli can be studied. This is difficult with noisy fMRI scanners.
EEG is completely non-invasive in comparison to most other neuroimaging techniques.

Using EEG also has disadvantages.

EEG gives tremendously low spatial resolution, hence it only gives a very ill mannered picture in the means of locality.
The electroencephalogram (EEG) is designed to measure electrical activity in the cortex, but it is not very good at detecting activity in subcortical areas. Because of the amount of artifacts that contribute to the data’s noise and the low signal-to-noise ratio, correctly interpreting an encephalogram necessitates a great deal of experience. Additionally, the signal becomes weaker the further away it is from the body’s surface. Some possibilities for noise are: heartbeat, muscle movements, eye movements and blinks, and inadequate grounding of the connection between the apparatus and body.

Module 1.7: Animal research role in understanding human behavior

The role of animal research in understanding behaviour.
The value of animal models in psychology research.
Ethical considerations in animal research.
“Animal research may give an understanding of human behavior”. In some sense this principle is a consequence of the first two principles: “Behavior is the product of physiology” and “Behavior can be genetically inherited”. The physiology and genetic set up of an animal and a human are the same, which naturally proves that to some extent the research of humans is generalizable to animals

The animal’s model value in psychology research.

The amount of animals used in psychological research annually in the USA alone has been estimated to be 1.25–2.5 million, and about 7.5% of psychological research is animal-based (Shapiro, 1998). The most popular species to be used in psychological research are rodents ,dogs, cats, pigeons, hamsters , chimpanzees and baboons.
The type of Research depends on the purpose of which animal is being used. 1. Researchers in the field of comparative psychology are interested in animal research as an end in itself.They either have an option to focus on a specific species or compare that kind of species to humans. Another group of researchers advocates the study of animals like the models of human beings and the expected result is that the result will be universal in nature and generalizable as well. 2. Human conditions like diseases are researched by the researchers by using animals to understand the particular disease..
An animal model is a concept that refers to using animal research to test a certain cause–effect hypothesis about a certain human behavior. So an animal model is not just broadly “using animals to understand human behavior”. It is a specific model. For example,There are few animal models which describe depression : stress models (which explain the onset of depression by being more exposed stress triggering situations), separation models (which explain depression by being separated or attachment issues ), medical models (which explain depression cause by the chemical imbalances in the brain), and more.
There are four types of experimental manipulation tried on animal models (Shapiro, 1998).
Invasive manipulations of the nervous system (parts of the brain are stimulated with electrodes, lesion, or removal) and genetic
manipulation of animals
Invasive manipulations with different body parts (parts may be restored by substances or damaged)
behavioral and environmental manipulations (such as electric shocks for rats based on the performance of the rat in the maze).
Comparison of animal and human brains seemingly conveys a very consistent story of evolution: as species evolved, new structures were built on top of older structures; so the deeper we go into the brain, the more “primitive” structures we will find.
There is a popular theory of triune brain proposed by MacLean (1990). This theory divides the human brain into three parts: a)reptilian complex, b)paleomammalian complex (the limbic system), and c)neocortex.
The idea is that the deeper brain structures can be found in animals as well; and the further down you go inside the brain, the further down you see in evolution. For example, the reptilian complex that you have in your brain should resemble the full brain of a reptile.

These are some of the advantages.

Animals and Humans are similar in many ways, specifically in terms of brain structure and genetically.
Studies with animal models do create results: Because of animal experiment many life saving treatments and useful models of human behavior have been developed gradually. For example, the discovery of insulin as done with the help of experimenting with dogs who had their pancreas removed Several animal studies gives allowance to researchers to work on full life span. While human subjects often outlive researchers themselves, laboratory mice live 2–3 years and this generates as an opportunity to see their nature beyond thor lifespan and even cross generations to generations. This is especially helpful in genetic research.
Animal research may be highly controlled. For example, the “knockout” technique has been developed to selectively switch off one of the genes in the DNA sequence. All other things being equal, this technique provides great insight into the function of individual genes. The ability to better control confounding variables means higher internal validity of experiments.
Animal subjects are relatively cheaper and can be easily accessed , easy to manage and manage.

Some of the disadvantages are as follows.

Animals and humans are not completely similar, and one can never know the extent of the differences between them. This means that animal research, if successful, still needs to be duplicated with humans in order to be sure that findings are generalizable.
Humans and animals can be similar in some biological aspects but they can completely differ psychologically. (Premack, 2007).
Researchers typically test new biomedical treatments for mental disorders using mouse models. The results of the rodent experiment, on the other hand, are never directly applied to humans. The drug needs to be tested first on larger animals, even if successful results are obtained using mouse models. It is analogous to a generalization pyramid, with humans at the top and rats at the bottom.
Since animals are subjected to testing in tightly controlled lab settings, it is possible that they are experiencing stress. As a result, their reactions to experimental manipulations may not be quite the same as in their natural environments: there may be an issue with ecological validity.
Despite their many similarities, animals and humans are fundamentally distinct. For instance In primates more than 85 antibodies for HIV have worked however it was not something very similar for people.(Bailey, 2008). On the contrary, some results that are negative in animals can actually turn out to be positive in humans. For example, Aspirin was proven dangerous to the animal kingdom but now it’s one of the widely used drugs amongst humans.

Examples of Animal Research


	Lashley conducted rodent experiments in which different parts of the vortex were removed to see if memory loss occurred during the maze.	Performance deterioration depends on the percentage of cortex destroyed but not on the location of the destroyed cells. This raises the question against the idea of localizing the memory function.
	Merzenich et al (1984): cortical hand representation of the hand in an adult owl.	As the brains’ matter was readjusted, it became in charge of other adjacent digits.

Ethical Considerations In Animal Research

Any animal study should be justified “with a clear scienti c purpose”. One of the following justi cations may be used. The study will: a)increase scientific knowledge of behavior b)Help us comprehend different species c)conclusions which are beneficial for human and other animals.
If non-human animals are selected for a particular research its compulsory to ensure that the species which are chosen are the best option to address the research question, and the least number of people required for the non human participants is used, a similar effect on animals.Before conducting the study, all animal research proposals must be submitted to the ethics committee. Psychologists and their assistants must be familiar with the specific characteristics of normal behavior in order to quickly identify animals that are stressed or unhealthy. Lab creatures should be given others conscious consideration. Whenever possible it is advised that the experiments should be designed in such a way that it should cause minimum or no harm to the species. APA guidelines also advise researchers to check with the painful stimuli to be made in use for non-human animals.
Euthanasia should be performed on any research animal that is observed to be suffering from chronic distress or pain that is not required for the purposes of the thesis study.
Special cautions are supposed to be taken with the animals who are there in the laboratories; they shouldn’t be let out in the wild.

Bateson’s cube: a model used to determine the usefulness of research.

This model asserts that three domains should he considered: a)the quality of the research b)the certainty of medical benefits and c)the degree of animal suffering.
Research that is of high quality, high benefit medically and low suffering in animals is seen to be worthwhile and has a good purpose. Likewise, poor quality research, with little benefit and high levels of suffering would be seen by this model to be unreasonable.
Bateson’s model is constructed in such a way that high levels of suffering in animals are unacceptable.
The cube denotes research that is acceptable [according to this model]. High suffering is never acceptable, but medium suffering in animals, high research quality and high levels of benefit would make the research permissible by these standards.

a) Replacement :- Replacement as a principle means that other research methods that replace animal research should be used wherever possible These include the use of cell cultures, human volunteers and computer modeling. b) Refinement :- Refinement means that research techniques that reduce pain and suffering in animals should be used wherever possible. c) Reduction :- reduction refers to using research strategies that are efficient and reduce the number of animal experiments used wherever possible.

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Two Key Studies of Neural Networks & Neural Pruning: Maguire (2000) & Draganski et al. (2004) ( SL IB Psychology )

Revision note.

Psychology Content Creator

You can use BOTH studies in a question on TECHNIQUES USED TO STUDY THE BRAIN and NEUROPLASTICITY (which could also appear as a 22-mark ERQ question). Maguire can also be used to answer a question on LOCALISATION OF FUNCTION

Key Study 1: Maguire (2000)

Aim: To investigate how neural networks form as a result of spatial navigation in London black cab taxi drivers

Participants: 16 healthy, right-handed male London black cab taxi drivers who had passed ‘The Knowledge’, a test of spatial navigation, aged 32-62 years with a mean age of 44 years. They had all been taxi drivers for at least 18 months, with the highest number of years as a taxi driver at 42 years

Procedure: The participants were placed in an MRI scanner and their brains were scanned. The MRI measured the volume of grey matter in the hippocampus of each participant, and this was then compared to pre-existing scans of 50 healthy, right-handed males (the control group ). The grey matter was measured using voxel-based morphemetry (VBM) which focuses on the density of grey matter and pixel counting

Results: The posterior hippocampi of the taxi drivers showed a greater volume of grey matter than that of the controls, who had increased grey matter in their anterior hippocampi compared to the taxi drivers. Maguire also carried out a correlational analysis which showed a positive correlation between the volume of posterior hippocampal grey matter and the length of time spent as a taxi driver

Conclusion: The posterior hippocampus may be linked to spatial navigation skills due to a specific neural network of cells within the posterior hippocampus

Evaluation of Maguire (2000)

Strengths

The study used a highly controlled clinical method of obtaining objective data which could then be easily compared and analysed
The correlational analysis of time spent as a taxi driver linked to increased volume of hippocampal grey matter lends validity to the idea that neural networks form as a result of learning and experience

Limitations

A correlation cannot show cause-and-effect so it is impossible to know whether the taxi drivers already had naturally high levels of hippocampal grey matter
Neural networks may have formed in the participants’ brain due to other, unknown factors
Spatial navigation
Posterior hippocampus
Neural networks

Key Study 2: Draganski et al. (2004)

Aim: To investigate whether structural changes in the brain would occur in response to learning and then ceasing juggling.

Participants: A self-selected sample of 24 adults aged 20-24 years old (21 female; 3 male) with no prior experience of juggling.

Procedure: The participants were randomly allocated to 2 conditions: jugglers or non-jugglers. Each participant underwent an MRI scan. Those in the juggling condition were taught a 3-ball cascade juggling routine. They were asked to practice this routine and to notify the researchers when they had mastered it. At that point the jugglers had a second MRI scan. After this second scan they were told not to juggle anymore and then a third and final scan was carried out 3 months later. The non-jugglers also underwent 3 separate MRI scans at pre-determined intervals.

Results : The MRI scans showed that there was no difference in grey matter in the brains of jugglers and non-jugglers at the time of the first scan (before the juggling practice began). At the end of the first part of the study, when the jugglers had been practising juggling, they had a significantly larger volume of grey matter in their mid-temporal cortex in both hemispheres (an area of the brain associated with visual memory , co-ordination, and movement).

Three months after the jugglers had stopped juggling the amount of grey matter in this region had decreased. However, the jugglers still had more grey matter after the study than at their first scan. The non-jugglers’ brains showed no changes at all from first to final scan.

Conclusion: Grey matter appears to increase in specific brain regions ( neuroplasticity ) in response to environmental demands (learning to juggle) and shrinks in the absence of that learning (stopping juggling). Thus, this study provides evidence for both neuroplasticity and neural pruning (and neural networks as it is via these that the learning takes place).

Evaluation of Draganksi et al. (2004)

This study has good internal validity as it took baseline measurements of the participants before the process began so as to ensure that real changes could be observed for comparison
The findings have a useful application as they can be used to inform possible interventions and therapies to offset degenerative brain conditions such as Alzheimer’s
This was a self-selecting sample which means that it is not representative of a wider population as self-selecting samples often share characteristics e.g. helpful, interested, extrovert
The participants were not in controlled conditions when they were learning to juggle so some of them may have over-practised, under-practised or not practised at all which would mean that the neural growth and pruning was due to other factors
Mid-temporal cortex
Visual memory
Structural changes

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Author: Claire Neeson

Claire has been teaching for 34 years, in the UK and overseas. She has taught GCSE, A-level and IB Psychology which has been a lot of fun and extremely exhausting! Claire is now a freelance Psychology teacher and content creator, producing textbooks, revision notes and (hopefully) exciting and interactive teaching materials for use in the classroom and for exam prep. Her passion (apart from Psychology of course) is roller skating and when she is not working (or watching 'Coronation Street') she can be found busting some impressive moves on her local roller rink.

Brain plasticity

Your brain’s plasticity is your brain’s ability to change. Your brain can create new brain cells, form new connections and change the structure of existing connections. Your brain adapts to best suit the tasks it is presented with. This means that focused training of specific abilities can produce enhanced abilities. Below, you will find links to some interesting research papers that shed light on brain plasticity as well as short descriptions of their key findings.

Plasticity in musicians (Gaser & Schlaug, 2003) A study of professional, amateur and non-musicians found that the grey matter (cortex) volume was highest in professional musicians, intermediate in amateurs and lowest in non-musicians in several brain areas involved in playing music, such as motor regions, visual input and object recognition.

Plasticity in bilinguals (Mechelli et al., 2004) It seems that brain plasticity is a factor in learning a second language. Bilingual brains have a larger left inferior parietal cortex than monolingual brains. This part of the brain is known to be concerned with language, mathematics and body image.

Plasticity in taxi drivers (Maguire, Woollett, & Spiers, 2006) London taxi drivers have a larger hippocampus than London bus drivers. The hippocampus is used to gather and process complex spatial information. The taxi drivers’ complex and ever changing routes through the city results in a greater need for navigational abilities than bus drivers who drive fixed routes. Their brains have thus adjusted accordingly.

Plasticity in students (Draganski et al., 2006) This study scanned the brains of a group of German medical students 3 months before and right after an important exam. It then compared the scans to scans of students who were not studying for an exam. The students who were studying for an exam showed learning-induced changes in the parietal cortex and posterior hippocampus, regions known to be involved in memory retrieval and learning.

We are going to expand this list and inform about other brain training related topics in the science section of our site. Subscribe to our newsletter and stay up to date on the most important scientific findings within neuroscience and brain training and news about Brain+.

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Temporal and Spatial Dynamics of Brain Structure Changes during Extensive Learning

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posterior parietal cortex
hippocampus
voxel-based morphometry
Introduction

One of the most exciting tasks of modern neuroscience is to uncover the functional and structural correlates of learning and memory. Recent theoretical work, as well as neuroimaging and psychological studies, has used a broad spectrum of stimuli to investigate different memory processes. The currently accepted view regarding memory is that items are first kept in the medial temporal lobe system followed by a consolidation process based on changes in the neocortex ( Miyashita, 2004 ) and that regions known to be active during perception and encoding are involved in the subsequent retrieval of learned information ( Nyberg et al., 2000 ; Shannon and Buckner, 2004 ).

Recent cross-sectional voxel-based morphometry (VBM) studies have demonstrated learning-dependent changes in the adult human brain and suggested anatomical correlates for navigation, arithmetic, linguistic, procedural, and musical learning abilities ( Maguire et al., 2000 ; Golestani et al., 2002 ; Sluming et al., 2002 ; Gaser and Schlaug, 2003 ; Draganski et al., 2004 ). Given the evidence from a recent longitudinal morphometric study showing that learning a complex visuomotor task induced task-specific transient gray matter changes in the adult human brain ( Draganski et al., 2004 ), we aimed to test the hypothesis whether extensive learning of abstract information can also induce morphological changes in cortical structures and whether these changes would be transient or long lasting. Based on well established evidence ( Eichenbaum, 2004 ; Squire et al., 2004 ), we predicted that the medial temporal lobe would show such structural changes.

The German preliminary medical exam, called “Physikum,” is usually taken after 2 years at the end of the preclinical education. It includes both oral and written exams in biology, chemistry, biochemistry, physics, human anatomy, and physiology. Consequently, the huge amount of new information, demanding a high level of encoding, retrieval, and usage, requires a 3 month period of daily study sessions and represents an ideal group for investigating possible learning-induced structural plasticity of the adult human brain.

Materials and Methods

T 1 -weighted magnetic resonance imaging scans of 38 medical students (21 female, 17 male; mean ± SD age, 24 ± 2.3 years) and 12 age- and sex-matched control subjects (8 female, 4 male; mean ± SD age, 22.1 ± 1.7 years) were performed at two time points [1.5 Tesla Siemens (Munich, Germany) Symphony scanner, magnetization-prepared rapid-acquisition gradient echo sequence yielding 150 sagittal slices with a defined voxel size of 1 × 1 × 1.08 mm]. In the student group, the first scan was obtained 3 months before the medical exam, and the second scan was performed on the first or second day after the exam. In 23 of these students, a third scan was performed 3 months later. The average grade of our group of volunteers matched the overall average grade of the medical exam that year, which was composed of 7043 medical students, suggesting that our cohort was representative of the population. The control subjects had no exams in the last 6 months and were not studying for any exams at the time. Additionally, they were carefully chosen in regard to educational status (college students for physical therapy) and were scanned at the same first two time points as the medical students.

The study was approved by the local ethics committee, and written informed consent was obtained from all study participants before examination.

VBM protocol

VBM is a whole-brain technique that is capable of discovering subtle, regionally specific changes in gray matter by averaging across subjects. VBM has been cross-validated with region-of-interest measurements and functional data in a number of studies ( Vargha-Khadem et al., 1998 ; May et al., 1999 ; Woermann et al., 1999 ). This method is based on high-resolution structural three-dimensional magnetic resonance images, registered in standard space, and is designed to find significant regional differences throughout the brain by applying voxelwise statistics within the context of Gaussian random fields ( Ashburner and Friston, 2000 ).

The data preprocessing and analysis were performed with SPM2 (Wellcome Department of Cognitive Neurology, London, UK) running under Matlab (MathWorks, Natick, MA). Preprocessing of the data involved spatial normalization, segmentation, modulation, and spatial smoothing with a Gaussian kernel ( Ashburner and Friston, 2000 ). We used a recently described optimized protocol ( Good et al., 2001 ).

Statistical analysis

Cross-sectional (cohort) analysis..

In the cohort analysis, we compared the medical students with the controls at the first time point using a two-sample t test to rule out potential differences between the groups.

Longitudinal analysis.

The longitudinal analysis for any changes in gray or white matter was performed using a repeated-measures ANOVA and was divided into two parts. In the first analysis, we included the medical students’ group over three time points only. We tested for any regions showing an increase in brain structure between the first and second time points. Alternatively, we also tested for a decrease between the first two time points. Furthermore, we tested for regions with an increase between the first, second, and third time point.

In the second analysis, we tested for a change in brain structure between the first and second time points by comparing the medical students with the controls, i.e., a group × time interaction. We applied a height threshold of p < 0.05 (corrected for multiple comparisons across the whole brain) and an additional spatial extent threshold (cluster level) of p < 0.001.

Regression analysis.

Additionally, we performed regression analyses using performance and gender as a covariate to test for possible correlations. Again, we applied a threshold of p < 0.05 (corrected for multiple comparisons across the whole brain).

Cohort analysis at baseline

The analysis showed no significant regional differences in gray matter between both groups.

Longitudinal analysis: whole-brain correction

The longitudinal analysis showed a significant increase in gray matter in the parietal cortex, namely in the posterior and inferior parietal lobule bilaterally [right, ( x , y , z ) (48, −77, 6), with t (59) = 10.5, p FWE < 0.001 (FWE indicates familywise error rate); left, (−43, −53, 27), with t (59) = 7.93, p FWE < 0.001], which decreased only nonsignificantly toward the third scan ( Fig. 1 ). In concretely looking for areas demonstrating an increase between the first, second, and third scans, the hippocampal increase in gray matter became significant [right, (38, −35, −6), with t (59) = 5.71, p FWE < 0.05] toward the third time point (3 months after the exam).

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Gray matter increase related to learning. Statistical parametric maps demonstrating the structural difference in gray matter during the learning period in medical students. The left side of the picture is the left side of the brain (L, left; R, right). A , Significant gray matter increase between the first two time points ( p < 0.05, corrected for multiple comparisons using FWE) in posterior parietal cortex is superimposed on the cortical surface of a representative single subject. B , Significant gray matter increase between the first, second, and third time points in the hippocampus. The image is superimposed ( p < 0.001 uncorrected) onto two selected slices of a representative single subject. The right hippocampus is significant at p < 0.05 (FWE corrected), and the left hippocampus is significant after application of a small volume correction using the hippocampal region as defined in the WFU PickAtlas ( p < 0.05, FWE corrected). C , Plots of percentage of signal change (black line) and 90% confidence interval (red line) averaged over the cluster of the right posterior parietal cortex (C1) and left hippocampus (C2) over the three time points. The gray matter increase in the parietal cortex had not changed significantly between the second and third scans during the semester break 3 months later. The posterior hippocampus showed an initial increase in gray matter during the learning period, which was even more pronounced in the third scan after the learning period.

A decrease in gray matter between the first two time points was found exclusively in the occipito-parietal lobe bilaterally [right, (18, −90, 12), with t (59) = 12.42, p FWE < 0.001; left, (−13, −93, 12), with t (59) = 10.46; p FWE < 0.001] ( Fig. 2 ).

Gray matter increases and decreases displayed as maximum intensity projection. Gray matter increases (red) and decreases (green) are simultaneously shown in a so-called maximum intensity projection, with threshold at p < 0.05 (corrected for multiple comparisons using FWE).

Testing for an increase between the first two time points using a group × time interaction and comparing the medical students and the controls, the above mentioned changes were found exclusively in the medical student group.

Longitudinal analysis: small volume correction

Our main analysis was performed with p < 0.05, corrected for multiple comparisons across the whole brain. Using this threshold, we found significant increases in the occipito-parietal lobe bilaterally and in the right hippocampus. Because this very conservative threshold might wrongly suggest lateralization of the hippocampus and considering our a priori hypothesis for the hippocampal area based on previous studies ( Maguire et al., 2000 , 2003 ; Squire et al., 2004 ), we repeated the same analysis using the hippocampal region as a region of interest. This so-called small volume correction (SVC) was applied with the hippocampal region as defined in the Wake Forest University (WFU) PickAtlas ( Maldjian et al., 2003 ), and we thresholded the result using a p < 0.05, corrected for multiple comparisons. Using the SVC, additionally to the described changes in the right hippocampus, the left hippocampal area demonstrated also an increase between the first, second, and third scans [(−19, −29, −9), with t (59) = 4.74, p SVC < 0.05].

Regression analysis

Testing for a correlation between gender or performance on the medical exam and changes in gray matter produced no significant results.

Using voxel-based morphometry, a whole-brain technique that is capable of discovering subtle, regionally specific changes in gray matter by averaging across subjects, we found learning-induced structural changes in the human brain, namely a gray matter increase in the posterior parietal cortex (PPC) and inferior parietal cortex bilaterally. In addition, and in partial contrast to this finding, there was a continuous gray matter increase in the posterior hippocampus throughout the three examined time points, demonstrating an increase even after the learning period. This differentiated temporal and spatial dynamic of morphological brain changes delineates the important role of subsystems in memory formation. We also tested for any decreases in gray matter as well as white matter changes and found a decrease of gray matter between the first and second time points exclusively in the occipital parietal lobe. These changes were, however, directly adjacent to a highly significant increase of white matter in this region, which is in accordance with the literature ( Golestani et al., 2002 ). An increase in white matter volume (i.e., a change of the classification of individual voxels from gray to white matter) will prompt an inverse effect (i.e., regional loss in gray matter volume) in adjacent gray matter. Because no hypothesis exists for a learning-dependant decrease of gray matter, we suggest that these changes are more likely linked to the described ( Golestani et al., 2002 ) regional increase in white matter. These findings have to be viewed with great caution because VBM is not sensitive for detecting changes in white matter.

Consistent with previous neuropsychological studies ( Shannon and Buckner, 2004 ; Wheeler and Buckner, 2004 ), our results place emphasis on the posterior and inferior parietal cortex in the network of declarative memory. These regions are associated with information transfer into long-term memory ( Miyashita, 2004 ). Recent studies using functional imaging have demonstrated the contribution of the PPC as a key neural locus for storage of visual short-term memory ( Linden et al., 2003 ; Todd and Marois, 2004 ). Neuroimaging data confirm the involvement of the dorsal and the ventral visual stream in learning and memory, in addition to their role in perception and encoding of visual information ( Buchel et al., 1999 ). Among other brain areas, the PPC is, beyond its role in the processes of space-based attention and motor intention, significantly involved in memory retrieval and memory success ( Wheeler and Buckner, 2004 ).

The gray matter increase in the right posterior hippocampus, known also for its role in semantic and spatial knowledge acquisition ( Alvarez and Squire, 1994 ; Maguire et al., 2003 ), suggests specific use-dependent plasticity of medial temporal lobe structures. The magnitude of the posterior hippocampal gray matter volume has been shown to correlate positively with spatial representation skills ( Maguire et al., 2000 ). This is probably not innate but depends on the extent of detail and/or duration of use of spatial representations ( Maguire et al., 2003 ). However, the cited morphometric studies compared two cohorts at one time point, depending on post hoc analyses to shed light on the relationship between gray matter differences and experience dependency ( Maguire et al., 2003 ). In this context, it is noteworthy that, beyond its key function as a gate to our long-term memory, the human hippocampus is one of the anatomical structures known for its neurogenesis activity, i.e., the ability to generate neurons derived from local stem cells ( Eriksson et al., 1998 ). Physical activity and an enriched environment, i.e., more opportunity for social interaction, physical activity, and learning, have been shown to improve the rate of neurogenesis and maintenance of these new cells ( Kempermann and Gage, 1998 ; Gage, 2002 ). Focusing on this issue, we used a regression analysis involving the performance (exam notes) of the students but found no correlation between changes in gray matter and performance. However, we did not control for IQ, learning strategies, or learning hours per day per week (workload), which might have revealed additional differences unrelated to performance.

Because of the limited knowledge regarding the neural code underlying the process of learning, we can only speculate about the nature of the dynamic structural changes. At the cellular level, it has been demonstrated that use-dependent plasticity of synaptic strength and structure is a fundamental mechanism involved in memory encoding ( Trachtenberg et al., 2002 ; Maviel et al., 2004 ). For both forms of memory storage, a particular synaptic growth is thought to represent the stable cellular change that maintains the long-term process ( Bailey et al., 2004 ). Given that the hippocampus is a well studied brain structure known for gating human long-term memory and being one of the brain areas involved in neurogenesis ( Eriksson et al., 1998 ; Kempermann and Gage, 1998 ; Gage, 2002 ), one could argue that the changes seen in the hippocampus in our study may in fact resemble the exciting neural changes seen in rodents ( Gould et al., 1999 ; van Praag et al., 1999 , 2002 ; Shors et al., 2001 ; Kempermann et al., 2004 ).

However, a simple increase in cell size or even a use-dependent synaptogenesis ( Trachtenberg et al., 2002 ) would probably have the same impact on our data. One could argue that the morphological changes in the parietal cortex resemble fast-adjusting neuronal systems, such as spine and synapse turnover ( Trachtenberg et al., 2002 ), whereas the progressive increase in the hippocampal area involves slow-evolving mechanisms such as neuronal or glial cell genesis ( Kempermann et al., 1997 ). The changes in gray matter volume of the posterior hippocampus past the point of the medical examination is surprising given the fact that the medical students had a break after their exam. One explanation for this phenomenon is that the intense preparation time necessary in preparing for the exam is also a very stressful episode. Intense psychosocial stress has been shown to reduce hippocampal volume and to cause reduced structural plasticity, including dendritic arborization, synapse density, and neurogenesis via elevated corticosteroid levels ( McEwen, 1999 ; Sauro et al., 2003 ). We can therefore presume that, during the acute study phase, stress-related factors as well as plasticity-enhancing factors were present, whereas after the exam, the continued effect of the cognitive stimulation became more detectable because counteracting stress responses were removed. Moreover, if neurogenesis is one of the contributing factors, we can also anticipate a delay in the increase of gray matter volume, because the generation and full maturation of new neurons in the adult hippocampus requires several weeks to months ( Zhao et al., 2006 ).

Independent of the precise nature of these morphological changes, our results support theoretical considerations stressing structural forms of neuroplasticity to be important for processing information in dynamic networks according to novel informational demands ( Chambers et al., 2004 ). It is reasonable to assume that plasticity is a characteristic of the nervous system that evolved for coping with changes in the environment. Understanding changes in brain structure as a result of learning and adaptation is pivotal in understanding the characteristic flexibility of our brain to adapt.

We thank all volunteers for their participation in this study and Gerhard Schuierer, Volker Busch, Michael Rose, and Eszter Schoell for technical support. A.M. is supported by Deutsche Forschungsgemeinschaft Grant MA 1862/2. C.B. is supported by Volkswagenstiftung and Bundesministerium für Bildung und Forschung. H.G.K. is supported by VolkswagenStiftung, Vetenskapsrådet, and LUA/ALF Göteborg.

Correspondence should be addressed to Dr. Arne May, Department of Systems Neuroscience, University of Hamburg, Martinistrasse 52, D-22046 Hamburg, Germany. Email: a.may{at}uke.uni-hamburg.de
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Culture Wires the Brain: A Cognitive Neuroscience Perspective

Denise c. park.

1 Center for Vital Longevity, University of Texas at Dallas

Chih-Mao Huang

2 Department of Psychology, University of Illinois at Urbana-Champaign

There is clear evidence that sustained experiences may affect both brain structure and function. Thus, it is quite reasonable to posit that sustained exposure to a set of cultural experiences and behavioral practices will affect neural structure and function. The burgeoning field of cultural psychology has often demonstrated the subtle differences in the way individuals process information—differences that appear to be a product of cultural experiences. We review evidence that the collectivistic and individualistic biases of East Asian and Western cultures, respectively, affect neural structure and function. We conclude that there is limited evidence that cultural experiences affect brain structure and considerably more evidence that neural function is affected by culture, particularly activations in ventral visual cortex—areas associated with perceptual processing.

There is a wealth of evidence that experiences sculpt both brain and behavior. Recent work in cognitive neuroscience has provided clear evidence that sustained experience changes neural structures. For example, London taxi drivers who engage in sustained wayfinding show larger gray matter of posterior hippocampi, with the magnitude of the effect increasing with experience, suggesting experience to be the causal mechanism ( Maguire et al., 2000 ). Canadian postal workers spend thousands of hours sorting postal codes by letters and numbers jointly, and this experience changes categorical representation of these two symbolic systems into a single more unitary system ( Polk & Farah, 1998 ). There is even evidence that sustained practice in learning to juggle increases the volume of cortical tissue in the bilateral midtemporal area and left posterior intraparietal sulcus ( Draganski et al., 2004 ) and that the effect generalizes to older adults ( Boyke, Driemeyer, Gaser, Buchel, & May, 2008 ).

As a trip to a foreign country often illustrates, values, behaviors, and environments differ markedly and systematically between cultures. Given the evidence described above showing that experiences affect the volume of neural structures and category organization, it is very reasonable to posit that sustained exposure to a set of cultural experiences and behavioral practices will affect neural structure and function. The burgeoning field of cultural psychology has provided innumerable demonstrations that there are subtle differences in the way individuals process information—differences that appear to be a product of cultural experiences. One seminal framework for understanding the impact of culture on cognitive function was proposed by Nisbett and colleagues ( Nisbett & Masuda, 2003 ; Nisbett, Peng, Choi, & Norenzayan, 2001 ; Peng & Nisbett, 1999 ). Nisbett and colleagues propose that East Asian and Western cultures have different biases for processing information that result from contrasting cultural values and beliefs. According to Nisbett et al. (2001) , Westerners, due to the individualistic, self-based focus of their culture, have a tendency to process central objects and organize information via rules and categories. In contrast, East Asians, based on their collectivist culture, tend to view themselves as part of a larger whole, resulting in a holistic information-processing bias in which object and contextual information are jointly encoded and in which relational information is prioritized over categorical information. This influential framework has received considerable support.

In this article, we briefly review behavioral evidence for this framework and consider evidence in particular suggesting that East Asians and Westerners differ in the information selected for attention, as measured by eye movements. We then focus on the consequences of cultural differences in information processing for neural structure and function. We first describe evidence from the functional imaging literature indicating that cultural differences exist in the ventral visual cortex (VVC)—an area of the brain highly associated with visual and perceptual processing. Evidence regarding neural differences in fronto-parietal function will be discussed next. Then we consider the few studies that address whether neural structures differ as a function of culture. Following that, we discuss the role of aging—which typically involves many years of immersion in a single culture—in understanding the relationship of cultural values and information processing biases to neural structure and function. We will close with the discussion of methodological considerations that need to be addressed in cross-cultural studies of neural structure and function. We should note that our focus on East Asian and Western culture should not be interpreted to indicate that this is the only, or even most important, value system that sculpts differences in cognition between cultures. Rather, this contrast is by far the most sophisticated and developed theorizing about culture’s relationship to cognition and it has been invaluable in developing a roadmap to direct the study of neural differences that result from different cultural biases for information processing.

Behavioral Data Demonstrating That Culture Affects Cognition

There is a well-developed literature suggesting that stable differences can be observed between East Asians and Westerners with respect to attention, contextual processing, categorization, and reasoning, with evidence that East Asians are more biased to process context, utilize categories less, and rely more on intuitive rather than formal reasoning processes. With respect to differences in context, Masuda and Nisbett (2001) reported that Japanese participants were more likely, after viewing pictures of fish swimming in an underwater environment, to recall contextual details than were Americans. They also found that when participants encoded pictures of wildlife against a complex natural background (e.g. a goat on a grassy meadow), Japanese participants’ recognition performance was more negatively affected by background changes than were Americans. Both of these findings are congruent with the notion that Japanese encoded information more holistically than Americans. In later work, Masuda & Nisbett (2006) reported that East Asians were more likely to detect changes in contextual information in a scene than were Westerners, a finding similar to that of Boduroglu, Shah, and Nisbett (2009) , who found that East Asians allocated attention to a broader spectrum of a visual display and were more likely to detect color changes in the periphery of a scene, whereas Westerners detected central changes most effectively. In another domain that demonstrated more East Asian attention to context, Masuda, Gonzalez, Kwan, and Nisbett (2008) reported that East Asian participants were more likely to include greater details and background when taking photographs of a model when they were free to set the zoom function of the camera as they saw fit. Kitayama, Duffy, Kawamura, and Larsen (2003) used the Frame-Line Test and asked Japanese as well as American participants to draw a line of either the exact same length as one presented in a frame or one that was proportional in size to the one presented in the earlier frame. Americans were more accurate in the absolute task, suggesting better memory for the exact or absolute size of the focal object, but East Asians were more accurate in the relative (proportional) task, suggesting better memory for contextual relationships. Overall, the findings converge from many different behavioral task domains to indicate that East Asians are biased toward holistic, contextual processing, whereas Americans are more biased to process focal objects in visual stimuli. Other data ( Chiu, 1972 ; Ji, Zhang, & Nisbett, 2004 ) provide convincing evidence that East Asians tend to process relationships among items more (e.g., cow–grass), whereas Westerners focus more on categories (e.g., cow–chicken), and there is also evidence that Westerners rely more on formal reasoning than intuition when the two or in conflict but that the reverse is true for East Asians ( Norenzayan, Smith, Kim, & Nisbett 2002 ).

Culture Differences in Eye Fixations for Complex Visual Stimuli

The culture and cognition framework discussed thus far would predict that East Asians should be more likely to fixate on contextual information than Westerners and that Westerners should tend to fixate more on central objects. Eye-tracking hardware permits measurement of both the duration and location of fixations and provides evidence for modulation of eye movements to visual stimuli by culture. Chua, Boland, and Nisbett (2005) examined the pattern of eye movement in East Asians and Westerners when viewing scenes with embedded central objects. Westerners fixated longer and more on focal objects, whereas Chinese participants had shorter fixation durations and more saccades to background scenes, confirming basic predictions of culture and cognition models. However, in a later eye-tracking study, Rayner, Li, Williams, Cave, and Well (2007) failed to find evidence for more attention to context in East Asians, but they did find evidence for shorter fixation length in the East Asians, a finding suggestive of more scanning of stimuli. More recently, Rayner, Castelhano, and Yang (2009) failed to find evidence for culture differences in processing unusual elements of a scene, which they suggest disconfirms the idea that culture biases oculomotor control. Goh, Tan, and Park (2009) also investigated eye movement in reaction to changes in complex scenes in East Asians and Westerners. East Asians and Westerners passively viewed pictures containing selectively changing objects and background scenes that strongly captured participants’ attention in a data-driven manner. They found that the number of object fixations in Westerners was more affected by object change than it was in East Asians. Also, in agreement with Rayner et al. (2007) , Westerners consistently maintained longer durations for both object and background fixations, with eye movements that generally remained within the focal objects. In contrast, East Asians had shorter fixation durations with eye movements that alternated between objects and backgrounds, consistent with a bias to process contextual relationship between objects and backgrounds. Taken together, the data on eye movement and scenes provides considerable evidence for culture differences in visual fixations, but more work is needed to understand the variables controlling culture differences in gaze duration to different scene elements.

There is also an emerging literature focused on cultural differences in processing of facial stimuli. Blais, Jack, Scheepers, Fiset, and Caldara (2008) presented consistent evidence that, when viewing faces, East Asians focus on a single central region of the face, whereas Westerners scan more broadly, focusing on both eyes and mouth. The authors note that the finding is potentially consistent with the idea that East Asians holistically process faces, but it could also reflect gaze avoidance that is characteristic of East Asian cultures. Either way, the data unquestionably lead to the conclusion that cultural factors play a role in the processing a facial information. In a later study, the same research group reported a pattern of cultural differences for processing emotional faces ( Jack, Blais, Scheepers, Schyns, & Caldara, 2009 ). East Asians were less effective than Americans at discriminating fear versus disgust and also showed a more limited scanning pattern for faces than did Americans who sampled the face broadly when judging emotions. The investigators conclude that their work broadly demonstrates that culture plays a role in modulating perceptions of emotion and suggest that these differences could be problematic for communication of emotion across cultures: “Easterners and Westerners will continue to find themselves lost in translation.” ( Jack et al, 2009 , p. 4).

At the most global level, the eye-tracking data make a case that East Asians and Westerners likely “see” different things when confronted with a complex visual stimulus. East Asians will sample elements of scenes more frequently and distribute gaze more broadly, consistent with the Nisbett et al. (2001) framework. However, the processing of faces yields a more complex picture, with some evidence that East Asians show less sampling in general and less sampling of emotional faces, limiting the accuracy of their diagnosis of emotion. Although more research is needed on the fixation data, both the cognitive-behavioral and eye-movement paradigms provide clear evidence to suggest cultural differences that should conceivably be reflected in patterns of neural activation and possibly even neural structures.

Neural Function and Culture

The literature on functional differences in activation patterns associated with culture is better developed than the structural literature. Han and Northoff (2008) thoroughly reviewed functional neuroimaging studies associated with culture variables, and Goh and Park (2009) reviewed studies focused primarily on cognitive processes. In this section, we consider functional imaging studies of cognition that focus on perception of scenes, objects, and faces, as well as studies that focus on social-cognitive variables.

The first functional magnetic resonance imaging (fMRI) study to focus on the ventral visual cortex (VVC) and demonstrate differences in functional activation between cultures was reported by Gutchess, Welsh, Boduroglu, and Park (2006) . East Asians and Westerners encoded pictures of individual objects (e.g., elephant alone), individual background scenes with no central object embedded (e.g., a jungle scene with no elephant), and background scenes with a target object embedded (e.g., elephant in a jungle). Congruent with the individualistic–collectivist hypothesis ( Miyamoto, Nisbett, & Masuda, 2006 ; Nisbett & Masuda, 2003 ; Nisbett et al., 2001 ), Westerners showed more activation in object processing regions, including the bilateral middle temporal gyrus, left superior parietal gyrus, and right superior temporal gyrus, although no reliable activation differences were observed in context-processing regions for Asians, as the individualistic–collectivist hypothesis would predict.

Other recent research has focused on the VVC. The VVC is a broad region encompassing a number of neural structures across mediotemporal and occipital lobes that is specialized for processing the identity of objects—the “what” pathway ( Mishkin, Ungerleider, & Macko, 1983 )—with many structures within this region characterized by a high degree of neural specificity. There is evidence that the fusiform region within the VVC activates selectively to faces but not to other categories of stimuli ( Kanwisher, McDermott, & Chun, 1997 ), and this region is often referred to as the fusiform face area (FFA). Selective responding to outdoor scenes, places, and houses occurs in the parahippocampal place area (PPA), and there is also evidence for specialization of object recognition in the lateral occipital complex ( Epstein, Graham, & Downing, 2003 ). The hippocampus, in addition to its other roles, binds objects to contexts and integrates relationships among scene elements ( Cohen et al., 1999 ). One method used to isolate regions of neural specialization within the VVC is through the use of an fMRI adaptation (fMR-A) paradigm. The fMR-A paradigm provides a means of measuring differences in selectivity and specialization in the VVC based on the phenomenon that brain response to repeated stimuli is typically reduced. This reduced activation provides an index of the brain’s ability to detect similarity between stimuli and reflects the use of less neural resources to process repeated information. Goh et al. (2004) used this technique to isolate brain regions that were involved in processing objects from those involved in processing scenes. In that study, participants passively viewed quartets of pictures in which each picture consisted of a central object embedded within a background scene ( Fig. 1a ). Within a quartet, the pictures were repeated such that (a) the object and background scene were presented four times, (b) the central object was changed while the background scene was held constant, (c) the background scene changed while the object was held constant, or (d) both objects and backgrounds scenes were changed across the quartet of pictures. This selective repetition of pictorial components allowed Goh et al. (2004) to isolate brain regions that were sensitive to either object repetition (object-processing regions) or background scene repetition (scene-processing regions). The object regions were observed to be localized in the lateral occipital regions, whereas repeated scenes induced adaptation only in parahippocampal regions.

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Cultural differences in the ventral visual cortex using the fMRI adaptation (fMR-A) paradigm, in which objects and backgrounds in the pictures were selectively repeated. a: Sample quartets stimuli used in the fMR-A paradigm. Each quartet consisted of four pictures of objects placed within background scenes. Within each of the four quartets, objects and background scenes in the pictures were either novel or repeated to isolate ventral visual regions that were sensitive to the either object or background scene repetition. b: Adaptation responses to background repetition in the parahippocampal regions (shown in light gray) were intact in all four groups. However, old East Asians showed significantly reduced object processing in the lateral occipital regions (shown in dark gray). This finding suggests that there is preserved context-focused processing across age and culture but that there are differences in object-based processing across cultures (adapted from Goh et al., 2007 ).

In a later study, Goh et al. (2007) utilized the same fMR-A paradigm to study neural differences in adaptation to objects and background context in East Asians and Westerners, both young and old. Participants were drawn from Singapore and the United States with careful matching of cognitive abilities as well as measurement of signal equivalence from scanner hardware ( Sutton et al., 2008 ). Results are displayed in Figure 1b , and they indicate that background processing was relatively similar across both age and culture, as the parahippocampal place area showed nearly equivalent activation across all conditions. The lateral occipital complex, indexed as an object processing region, however, showed an Age × Culture interaction, with generally less efficient processing of objects by older adults. However, the object area adaptation was greatly attenuated in elderly East Asians than in Westerners, suggesting that object-processing regions decline with age disproportionately in East Asians. The findings demonstrate the malleability of perceptual processes by culture, with evidence that efficient object processing by young adults becomes more subject to cultural variations with age in the directions predicted by individualistic–collectivistic models of culture and cognition ( Miyamoto et al., 2006 ; Nisbett & Masuda, 2003 ; Nisbett et al., 2001 ).

In another subsequent study that examined culture effects in an adaptation paradigm, Jenkins, Yang, Goh, Hong, and Park (2010) assessed cultural differences in neural adaptation to congruent and incongruent scenes. The incongruent scenes were created by placing an object against a background where it would not commonly be found (e.g., a cow in a kitchen). Results indicated that Chinese participants showed greater adaptation to the incongruent scenes in the lateral occipital complex, an object processing area. The findings suggest that the Chinese devoted more neural resources to object processing when the scenes were incongruent due to their enhanced sensitivity to the entire scene, whereas Americans were less likely to be affected by incongruent context, as they focus primarily on objects.

Although much of the functional imaging work has focused on the VVC, there is also evidence for cultural differences in fronto-parietal function. Hedden, Ketay, Aron, Markus, and Gabrieli (2008) conducted a modified framed-line test and examined the neural network activated when East Asian and Western subjects made judgments of line length that were either proportional to a box drawn around the line or were absolute and independent of the box. East Asians engaged more fronto-parietal activity ( Fig. 2 ) when they made the absolute or context-free judgment, whereas Westerners showed more engagement in the condition requiring them to integrate the line with context. This provides an elegant demonstration of modulation of neural resources to support culturally preferred or nonpreferred tasks, with nonpreferred tasks requiring greater resource.

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Neural activation in frontal and parietal brain regions when Westerners and East Asians perform both of the absolute and relative length judgments in a modified framed-line test. Participants from different cultures display activation in similar networks, but the regions known to be associated with attentional control showed greater activation during culturally nonpreferred judgments than during culturally preferred judgments (adapted from Hedden et al., 2008 ).

There is also an emerging literature suggesting that cultural values influence neural networks activated when recognizing and thinking about self or others. Chiao et al. (2008) demonstrated that native Japanese in Japan and Caucasians in the United States showed greater amygdala activation to fear expressed by members of their own cultural group, suggesting that the automatic, prepotent nature of the amygdala response to fear faces is modulated by culture. Zhu, Zhang, Fan, and Han (2007) reported that both East Asians and Westerners showed robust activation in the medial prefrontal cortex (MPFC) and anterior cingulate cortex when making judgments about self. When the same participants made judgments about their mother, the East Asian subjects showed more MPFC activation than did Westerners, reflecting the more collectivist view of self, in contrast to the Western individualistic representation. In a later event-related potentials study, Sui, Liu, and Han (2009) demonstrated that the British participants showed a larger anterior negative activity at 280–340 ms when responding to photo of their own face than those of a familiar face (i.e., a friend’s face), whereas Chinese participants showed a reverse pattern, reflecting the cross-cultural differences in the neural correlates of self and other-referencing stimuli. Moreover, Chiao et al. (2009) also reported neural activation of the MPFC when making judgments about self or others depending on the strength of collectivistic or individualistic values. Similarly, Hedden et al. (2008) demonstrated that the more acculturated the East Asian participants were to Western individualistic culture, the stronger they showed the Western pattern of neural activation. Of particular interest was that the degree individuals from East Asian and Western cultures endorsed individualistic or collectivistic values, rather than culture of origin, determined neural activations. This is a particularly important study because it demonstrates that values associated with representation of self shape neural activations, making a compelling case for cultural values shaping neural function, at least in terms of representation of self.

Structural Differences in Brains Between Cultures

There is a small literature that has developed that examines the possibility that structural differences exist between East Asian and Western brains. The literature reviewed earlier indicating that life experiences with wayfinding ( Maguire et al., 2000 ) and juggling ( Boyke et al., 2008 ; Draganski et al., 2004 ) affects brain structure makes a strong case for the hypothesis that decades of exposure to cultural values or practices could shape or mold neural structures. In an early study, Zilles, Kawashima, Dabringhaus, Fukuda, and Schormann (2001) compared 56 Japanese and 56 European brains using MRI and 3-D reconstruction techniques. They reported evidence for intersubject variability that was related to cultural group and gender, with Japanese hemispheres being relatively shorter but wider than European hemispheres. Kochunov et al. (2003) examined brains of Chinese-speaking Asian and English-speaking Caucasian adults, all of whom dwelt in the United States, using deformation field morphometry. They reported four small regions across frontal, temporal, and parietal areas that were significantly larger in Chinese than in Americans and interpreted the results as being due to the orthographic, phonetic, and even semantic characteristics of speaking Chinese rather than genetic differences. They argued that cognitive strategy differences involved in language acquisition and usage molded brain form. Green, Crinion, and Price (2007) reported that a voxel-based morphometry (VBM) analysis of the brains of monolingual versus multilingual speakers also yielded evidence for greater gray matter density in Chinese speakers, regardless of whether they were Chinese or European. Greater density was reported in left superior and middle temporal gyri as well as the right superior temporal and left inferior frontal gyrus, and again, the interpretation was that these areas had greater volume due to the challenges of speaking Chinese.

In a recent study, Chee, Zheng, Goh, and Park (2010) collected structure MRI data using measures of cortical thickness and density on a sample of 140 participants that were drawn from four groups: young and old Singaporeans of Chinese ethnicity and young and old Americans of non-Asian ancestry. There were between 31 and 39 participants in each group and young adults from the two cultures were well matched for neuropsychological assessment such as speed of processing and working memory, as were old adults (who performed more poorly than young adults). Chee et al. (2010) reported that the volume of structures was generally equivalent in the young adults from the two cultures and that volume declined across many structures with age. When measures of cortical thickness were calculated, young Americans showed greater thickness in a number of frontal areas, as well as the right superior parietal lobule, in comparison with Asians. Only one region was thicker in Asian young and this was in the left inferior temporal gyrus (Brodmann Area 37). The increased density for frontal areas was confirmed with an alternative measure (VBM), suggesting the reliability of the cultural effect. There were no differences in older adults, partially because of the increased variability of thickness within each group of older adults. The authors suggested that the increased thickness in the frontal areas of young Westerners could conceivably be due to the increased focus Western culture puts on reasoning, problem solving, and independent thinking, whereas the East Asian cultures rely more on following direction and rote memory. However, alternate explanations were also considered, such as dietary, genetic, and environmental differences unrelated to culture per se.

Although the literature on brain structural differences as a function of culture or ethnicity is sparse, the extant literature suggests that this is an important and fertile area of investigation. We tentatively suggest that hypothesis-driven research in which specific regions of interest are related to specific behaviors engaged in by the two cultures differentially, such as differences in linguistic properties, may be the most likely to pinpoint clearly attributable differences in cultural practices or values. Reliable differences are of great interest because they provide insight into domains of neuroanatomy that are modifiable by experience and into structures that are invariant regardless of experiences.

Aging, Culture, and Cognition

The study of life-span differences in neurocognitive function across cultures is an important topic that can inform our understanding of the aging process as well as culture-associated neuroplasticity (see reviews by Park, 2008 ; Park & Gutchess, 2002 , 2006 ; Park, Nisbett, & Hedden, 1999 ). The contrast of culture and aging allows for a simultaneous examination of the contributions of experience and biology to the process of aging. Behaviorally, the evidence to date suggests that the effects of aging are much larger than the effects of culture on free recall in memory ( Gutchess et al., 2006 ), source memory ( Chua, Chen, & Park, 2006 ), working memory ( Hedden et al., 2002 ) and processing speed ( Hedden et al., 2002 ). These data suggest that the basic “hardware of the mind” declines in a robust manner with age and that the process does not appear to be mitigated very much by cultural experiences. However, the neural data lead to similar but slightly more complex conclusions. The cross-cultural differences in brain structural data reported by Chee et al. (2010) from a large sample of carefully matched old and young adults suggest that there are pronounced, reliable differences in volume of frontal, temporal, and parietal regions with age. Moreover, the magnitude of the volumetric differences are similar for old and young adults, suggesting the strong role of biology rather than environment in mediating age changes in brain structure, as the experiences of the older adults differ markedly across the samples. At the same time, Chee et al. (2010) note that it is possible that the high degree of variability in volumes that occurs with age makes it difficult to assess any systematic differences, suggesting that very large samples, as well as detailed knowledge about experiences, would be required to detect differences. There is only one published study to date on functional neuroimaging data that includes a cross-cultural comparison of young and old adults ( Goh et al., 2007 ). This study suggested that culture effects that were absent in young adults emerged when older adults were studied. That is, young East Asians and Westerners showed equivalent object processing activations, but significant age-related differences emerged with age, with old East Asians evidencing a nearly complete absence of an object-processing area. This decreased object processing in older East Asians reflected a bias to process context over objects rather than an inability to engage in object processing. The same elderly subjects were tested in an fMR-A study by Chee et al. (2006) , but they were instructed to focus attention on the object in the pictures they studied. Under these conditions, a robust object-processing area emerged, but activation in the parahippocampal areas (specialized for processing background scenes) declined, suggesting that the older East Asians had an intact object-processing area, but a limited attentional capacity that prevented them from engaging both object and background regions. With age, the cultural bias to process context over objects emerged in East Asians. These data illustrate the importance of culture in shaping neural functioning, but they also demonstrate the flexibility of the brain and the fact that the cultural changes represent processing biases rather than immutable circuitry changes, as the culture effects were “overridden” by instructions to attend to objects.

There are many important questions that remain in the cognitive neuroscience of aging ( Park, 2008 ). Park et al. (1999) argued that with age, both cultures would move toward a more balanced representation of self and others, leading Westerners to become less oriented to self and East Asians to conceivably become more self-focused. Many critical studies remain to be done that will allow us to understand what aspects of the brain are immutably changed by the biology of aging and which aspects are sculpted by cultural experiences.

Methodological Considerations Associated With Neuroimaging Culture Differences

The study of cultural differences in neurocognitive function is fraught with potential confounds and hazards that cloud interpretation of the data. The scope of this issue could easily encompass an entire volume. The focus here will be on three considerations particularly salient to neuroimaging studies. First, in conducting cross-cultural imaging work, it is important to recognize that neuroimaging data is very different from behavioral data. The dependent measure in an MRI study consists of t values for roughly 30,000 to 35,000 voxels of data, which if collected functionally, are typically sampled every 2 s, providing literally millions of data points as outcomes. This is quite a contrast with cognitive behavioral data that often involves only a few measures of memory, reaction time, or attention. Moreover, the data are collected from two groups of participants who typically differ in many systematic ways besides their cultural values, rendering interpretation of any differences found quite difficult. It is therefore critical that specific hypotheses grounded in knowledge of neural structures and behavioral data be tested ( Park, Nisbett, & Hedden, 1999 ). As the above review of the behavioral data indicate, there is a wealth of evidence that visuo-perceptual processes differ between East Asian and Westerners. For this reason, it made sense for the initial work our research group did on neurocultural differences to focus on the VVC, an area of the brain associated with object recognition, contextual processing, and binding of scene elements. This allowed us to test specific hypotheses in regions of interest and limit the amount of neural “real estate” under investigation, increasing the prospects of finding interpretable, replicable differences that are related to cultural values and beliefs rather than to differences in diet, genetics, or medication usage (which, thus far, has always been higher in Western samples than in East Asian samples that we have tested).

A second issue to keep in mind when conducting cross-cultural studies of cognition is the importance of collecting some objective measure of performance suggesting groups are matched. Figure 3 presents neuropsychological data reported by Hedden et al. (2002) from a sample of old and young adults tested in China and the United States. The study demonstrates clearly that when numerically based tests of speed of processing (digit comparison) and working memory (backward digit span) were used, young Chinese showed superior performance to young Americans. Some research suggests that Chinese is less syllabically dense than English and permits more efficient rehearsal ( Cheung & Kemper, 1993 , 1994 ), resulting in an apparently greater working memory span for Chinese. When more neutral, spatially based tasks were used (pattern comparison for speed of processing and backward Corsi blocks for working memory), young and old participants were matched, providing good evidence for equivalence in ability ( Fig. 3 ). When conducting studies of culture differences in cognition, it is very helpful to demonstrate that the groups selected for study are matched in basic component cognitive abilities like speed of processing and working memory ( Park et al., 1999 ), as differences observed between cultures in cortical thickness or patterns of neural activation cannot then be attributed to a confounding of basic cognitive abilities with culture. The Hedden et al. (2002) study as well as a number of others (e.g., Gutchess, Welsh, Boduroglu, & Park, 2006 ; Jenkins et al., 2010 ) detail measures that are useful for demonstrating equivalence in East Asian and Western samples on a number of cognitive tasks.

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Object name is nihms377037f3.jpg

Cross-culture measures of verbal and visuospatial versions of speed of processing and working memory across the life span. Cultural equivalent performances were observed on the visuospatial measures of both working memory and speed of processing for either age group. However, the numerically based measure of both working memory and speed of processing show evidence of cultural and linguistic biases (adapted from Hedden et al., 2002 ).

The third issue to consider when collecting neuroimaging data between cultures is the potential hazards that exist if one is collecting data from two different MRI machines, with each instrument associated with a particular culture. Again, if one finds differences in the blood oxygen level-dependent (BOLD) signal between cultural groups, it is possible that the difference could occur as a result of differing properties between hardware, such as MRI machines and imaging coils, rather than differences in the activation patterns between cultures ( Park & Gutchess, 2002 ). We have conducted some large cross cultural structural and functional imaging studies between Singapore and the United States, with both groups having identical imaging hardware and software. There was little data reported on between-scanner variability, and we wanted to be certain differences we observed between groups were due to culture differences rather than signal differences between imaging hardware. To assess this issue, we collected functional imaging data with a visual and motor task from 4 participants who were repeatedly imaged in identical 3-Tesla MRI machines both in Singapore and the United States, with two sessions at each site ( Sutton et al., 2008 ). Data showed that there was minimal variance in BOLD signal as a function of site and that between-subject differences accounted for 10 times more variance than did site of data collection. Task variables (motor vs. visual) naturally also accounted for significant variance. We also routinely conducted a phantom scan before testing participants to evaluate noise and stability of the two scanners and reported results to be sure the two magnets were similarly calibrated. The data provided assurance that reported differences between cultures were not due to differing signal properties of the MRI machines between two sites.

Conclusion and New Directions

There is clear evidence that cultural values and experiences shape neurocognitive processes and influence patterns of neural activation and may even effect neural structures. The study of the “cultural brain” is a critically important topic that demonstrates how fundamental cultural values and practices are at influencing thought. An important direction for cognitive neuroscience of culture will be to develop broader frameworks that go beyond East Asian and Western cultures and to consistently consider the possibility that observed effects may not be determined by cultural values or experiences but may instead result from differences in diet, health, and even genetics. The focus on quantifying degree of identification with cultural values and its relationship to brain structure and function is important, as it provides validation that cultural values are controlling effects, in light of the many other sources of variance between different cultures. There is a clear need for multimodal imaging—the integration of structural differences with functional data, as well as an understanding of neural activations that occur when eye movement differences are found. The developmental trajectory of cultural differences also seems like an extraordinarily important domain that is relatively unexplored. How early in the life span do cultural values sculpt the brain? Similarly, does sustained exposure to a culture across one’s lifespan enhance the effects of cultural values? This research is an important domain for understanding the malleability of the human brain and how differences in values and social milieus sculpt the brain’s structure and function.

Acknowledgments

This work was supported by National Institute of Aging Grants R01 AGO15047 and R37 AGO60625 awarded to Denise Park.

Reprints and permission: sagepub.com/journalsPermissions.nav

Declaration of Conflicting Interests

The authors declared that they had no conflicts of interest with respect to their authorship or the publication of this article.

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Psychology IBDP: Localisation of function – Relevant research studies

Read our latest blog-post for students currently studying psychology for the IBDP from Pamoja teacher, Peter Anthony

Localisation of function is the second topic area of the Biological Approach to understanding behaviour.

You need to understand the theory that behaviour, emotion, and/ or thoughts originate in specific regions of the brain.

Maguire (2000) is relevant to this topic as well as techniques used to study the brain in relation to behaviour .

This is an excellent example of how you can economise on the number of studies you need to learn during the course. Maguire (2000) is highly recommended for any response to an SAQ on this topic.

For an ERQ, you would need to supplement Maguire (2000) with another study, either Draganski et al. (2001) or Tierney et al. (2001). Draganski is recommended as you have already encountered this investigation in your study of brain imaging technology.

Links to original studies: Maguire (2000) Draganski et al. (2004)

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ESTUDIOS DE DRAGANSKI Y COLABORADORES (2004, 2006)
ESTUDIOS DE DRAGANSKI Y COLABORADORES (2004, 2006)
Draganski et al. (2006)
Prevention of dementia: An overview of European Studies Laura
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Research Methods Approaches to researching behaviour.

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Draganski et al. (2006) Flashcards
Terms in this set (9) 2006. Draganski et al. biological. The purpose of this study was to investigate the impact of extensive learning on the brain. lab. unknown. 38 medical students and a control group of 12 participants matched for age and sex.
Draganski et al (2004)
Draganski — IB Psychology. Aim: To investigate whether structural changes in the brain would occur in response to practicing a simple juggling routine. 24 volunteers, 21 female and 3 male. They are all non-jugglers and were split into the jugglers and the control group. Jugglers' and non-jugglers' brains are scanned before any form of ...
Temporal and Spatial Dynamics of Brain Structure Changes during
The current view regarding human long-term memory as an active process of encoding and retrieval includes a highly specific learning-induced functional plasticity in a network of multiple memory systems. Voxel-based morphometry was used to detect possible structural brain changes associated with learning. Magnetic resonance images were obtained at three different time points while medical ...
Draganski et al (2006) Flashcards
Draganski et al (2006) Aim. Click the card to flip 👆. To investigate possible learning-induced structural plasticity of the adult human brain as well as investigate functional and structural correlates of learning and memory. Click the card to flip 👆. 1 / 6.
Draganski et al. (2006) Flashcards
The Biological Approach: neuroplasticity, techniques used to study the brain Learn with flashcards, games, and more — for free.
Temporal and spatial dynamics of brain structure changes ...
The current view regarding human long-term memory as an active process of encoding and retrieval includes a highly specific learning-induced functional plasticity in a network of multiple memory systems. Voxel-based morphometry was used to detect possible structural brain changes associated with lea …
Chapter 4: Biological Approaches to Understanding Behaviour
You can use Maguire et al.'s study and Draganski et al's (2004) research as key studies in this section on neuroplasticity, just as you can in the section on brain imaging techniques and MRI scans, and the section on localization (above).
Changes in grey matter induced by training
We used voxel-based morphometry, a sophisticated objective whole-brain technique, to investigate subtle, region-specific changes in grey and white matter by averaging results across the volunteers ...
Neuroplasticity: Changes in grey matter induced by training
This discovery of a stimulus-dependent alteration in the brain's macroscopic structure contradicts the traditionally held view that cortical plasticity is associated with functional rather than anatomical changes. Does the structure of an adult human brain alter in response to environmental demands? Here we use whole-brain magnetic-resonance imaging to visualize learning-induced plasticity in ...
IBDP Psychology Chapter 2 Notes: Biological Approach to Behavior
Example 2 — Draganski et al (2006):increasing the amount of gray matter in the parietal cortex and posterior hippocampus by studying a lot of abstract material. Draganski et al (2006) glanced at 12 subjects of control and about 38 students studying medical matched for the age and gender. 1.
Two Key Studies of Neural Networks & Neural Pruning: Maguire (2000
Revision notes on Two Key Studies of Neural Networks & Neural Pruning: Maguire (2000) & Draganski et al. (2004) for the SL IB Psychology syllabus, written by the Psychology experts at Save My Exams.
Brain plasticity is the basis for brain training
Plasticity in students (Draganski et al., 2006) This study scanned the brains of a group of German medical students 3 months before and right after an important exam.
Mindfulness practice leads to increases in regional brain gray matter
For example, longitudinal studies have shown task-specific increases in brain gray matter as an effect of acquisition of abstract information ( Draganski et al., 2006 ), motor skills ( Draganski et al., 2004 ), aerobic training ( Colcombe et al., 2006 ), and cognitive skills ( Ilg et al., 2008 ).
Temporal and Spatial Dynamics of Brain Structure Changes during
Recent cross-sectional voxel-based morphometry (VBM) studies have demonstrated learning-dependent changes in the adult human brain and suggested anatomical correlates for navigation, arithmetic, linguistic, procedural, and musical learning abilities ( Maguire et al., 2000; Golestani et al., 2002; Sluming et al., 2002; Gaser and Schlaug, 2003; Draganski et al., 2004 ). Given the evidence from a ...
Temporal and Spatial Dynamics of Brain Structure Changes during
These structural changes are evident in the case of self-regulation (Hölzel et al. 2011;Tang et al. 2012), as well as in the acquisition of abstract information (Draganski et al. 2006), motor ...
Culture Wires the Brain: A Cognitive Neuroscience Perspective
The literature reviewed earlier indicating that life experiences with wayfinding ( Maguire et al., 2000) and juggling ( Boyke et al., 2008; Draganski et al., 2004) affects brain structure makes a strong case for the hypothesis that decades of exposure to cultural values or practices could shape or mold neural structures.
Psychology IBDP: Localisation of function
For an ERQ, you would need to supplement Maguire (2000) with another study, either Draganski et al. (2001) or Tierney et al. (2001). Draganski is recommended as you have already encountered this investigation in your study of brain imaging technology.
PSYCHOLOGY
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SOLUTION: Draganski et al 2006
Aim: To detect possible structural brain changes associated with learningProcedure: The subjects will learn a large amount of abstract material in
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Recent cross-sectional voxel-based morphometry (VBM) studies have demonstrated learning-dependent changes in the adult human brain and suggested anatomical correlates for navigation, arithmetic, linguistic, procedural, and musical learning abilities ( Maguire et al., 2000; Golestani et al., 2002; Sluming et al., 2002; Gaser and Schlaug, 2003 ...
Draganski et al. (2004) Case Study
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Temporal and spatial dynamics of brain structure changes during extensive learning

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Chapter 4: Biological Approaches to Understanding Behaviour

2.2 Case Studies

4.3 Assessment Advice

Myths and Misconceptions

2.1 Correlation Studies

Focus on Research – a twin study (correlational study)

Focus on Research – a case study – H.M.

Focus on Research – experiment – Antonova et al. (2011)

Focus on Research - example of a study using MRI scans

Focus on Research - example of a study using a PET scan - Tierney et al. (2001)

Neural networks

Focus on Research – neuroplasticity and neural networks - Maguire et al. (2000)

Neural pruning

Focus on research – neuroplasticity and neural pruning – Draganski et al. (2006)

Excitatory and inhibitory synapses

Agonists and Antagonists

Focus on Research – serotonin - Walderhaug et al. (2007)

Focus on Research – acetylcholine – Martinez and Kesner (1991)

Focus on Research – testosterone – Carré et al (2016)

Focus on Research – testosterone – Nave et al. (2017)

4.2 Pheromones and Their Effects on Behaviour

Focus on Research – putative (possible) human pheromone – Wedekind et al. (1995)

Focus on Research – argument against human pheromones – Doty (2010)

Focus on Research – epigenetics – Suderman et al. (2014)

Focus on Research epigenetics - Weaver et al. (2004)

Twin studies

Focus on Research – correlational (twin) study – McGue et al. (2000)

Focus on Research – correlational (twin) study – Kendler et al. (2006)

Limitations of twin studies

Kinship (Family) studies

Focus on Research – correlational kinship (family) study – Fernandez-Pujals et al. (2015)

Focus on Research – evolutionary adaptation of disgust – Curtis et al. (2004)

Focus on Research – sexual selection – Buss et al. (1992)

Limitations of evolutionary psychology

6.2 The value of animal models in research into the brain and human behaviour

6.3 The value of animal models in research into hormones and/or pheromones.

Focus on research – testosterone – Albert et al. (1986)

6.4 The value of animal models in research into genetics and behaviour

6.5 Ethical considerations in animal research

6.6 Assessment advice

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Changes in grey matter induced by training

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Neuroplasticity: Changes in grey matter induced by training

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Plasticity in gray and white: neuroimaging changes in brain structure during learning

biological approach to behavior Notes

What will you learn in this section

Brain structure

b) Cerebellum

c) Limbic System

Localization

Hemispheric Localisation

Motor centers

Somatosensory cortex

Visual center

Auditory center

Language centers