# Physiology and Behaviour

The physiology and behaviour (PB) outcomes focus on how brain structures influence particular behaviours.
There are seven physiology and behaviour outcomes:
* PB1: Explain localisation using a key study as an example.
* PB2: Explain one study related to localisation of function in the brain.
* PB3: Using one or more examples, explain effects of neurotransmission on human behaviour.
* PB4: Using one or more examples, explain functions of two hormones in human behaviour.
* PB5: Discuss two effects of the environment on physiological processes.
* PB6: Examine one interaction between cognition and physiology in terms of behaviour. Evaluate two relevant studies.
* PB7: Discuss the use of brain imaging technologies in investigating the relationship between biological factors and behaviour.
Note that any example responses are not necessarily worth full marks, but exist simply to provide an idea of how an example looks.

# PB1

Explain localisation using a key study as an example.
The command term explain is a level two command term, and is asking you to give a detailed account including reasons or causes. This outcome cannot be asked in an essay form and is therefore worth 8 marks.

## Example response

There is no example response yet for this outcome.

## Additional Notes

There are no additional notes yet for this outcome.

# PB2

Explain one study related to localisation of function in the brain.
The command term explain is a level two command term, and is asking you to give a detailed account including reasons or causes. This outcome cannot be asked in an essay form and is therefore worth 8 marks.

## Example response

There is no example response yet for this outcome.

## Additional Notes

There are no additional notes yet for this outcome.

# PB3

Using one or more examples, explain effects of neurotransmission on human behaviour.
The command term explain is a level two command term, and is asking you to give a detailed account including reasons or causes. This outcome cannot be asked in an essay form and is therefore worth 8 marks.
Neurotransmission refers to the method by which electrical impulses are transferred across the synapse once intensity is reached. A neurotransmitter is a chemical that is released from a neuron to relay information to another cell. Neurotransmitters are stored in membranous sacs called vesicles in the axon terminal. Each vesicle has thousands of chemicals of a neurotransmitter. There are several neurotransmitters:
* Acetylcholine
* Serotonin
* Dopamine
* Norepinephrine (noradrenaline)
* Epinephrine (adrenaline)

## Acetylcholine

Acetylcholine (ACh) is a neurotransmitter that has several key functions. These include muscle contraction, conversion and consolidation of memories, and dendric branching (learning, attention, and concentration). A particular human behaviour that is associated with a lack of ACh is Alzheimer's Disease. When ACh levels in the body are high, concentration and memory consolidation also increases because if someone is more attentive when learning and actively consolidating the memory, they will tend to remember more. Hence, when ACh is low, concentration and consolidation decrease, reducing the amount of information that is remembered. This is what occurs in Alzheimer's Disease: ACh is low, as is the ability to recall information (because of a lack of attention and consolidation).
    Supporting Study: Martinez and Kesner (1991) was a key study that investigated the role of acetylcholine (ACh) on memory. The rats were trained to solve a maze and then, once they were successful, were randomly allocated into three conditions: rats that were injected with scopolamine (a drug that inhibits ACh levels), rats that were injected with physostigmine (a drug that increases ACh levels), and a control group. The rats were then sent through the maze again. The results showed that the scopolamine group had the slowest time and made the most errors, whereas, the physostigmine group was the quickest and mad the fewest errors. This shows that ACh plays a role in attention, concentration and learning, which aid in memory.
       Link: Squire (1985) conducted a similar experiment, investigating the effects of ACh on Alzheimer's disease. He found that participants with lower levels of ACh concentrated in the hippocampus tended to develop Alzheimer's disease when they were older.
The behaviour is forgetting or Alzheimer's Disease.

### Functions

Therefore, the functions of acetylcholine are controlling:
* muscle contraction
* conversion and consolidation of memories
* learning, attention, and concentration (dendric branching)

### Behaviours

The human behaviour is forgetting or Alzheimer's Disease.

## Serotonin

Serotonin plays an important role in attempting to maintain homeostasis within the body. It does this through its several functions, including: mood regulation, emotion, appetite, sensory perception, sleep, arousal levels, and temperature regulation. If these functions are affected by environmental influences, then serotonin will increase in order to try to regulate them, which is done through the activation of the hypothalamus and frontal cortex. When someone is deprived of food (appetite), sleep, conversation and entertainment (arousal levels), and warmth (temperature regulation), then this activates the hypothalamus and frontal cortex (because they have many serotonin receptors). Hence, this can cause the behaviour of a changed perception of the environment (i.e. hallucinations) because the hypothalamus has functions similar to those of serotonin, and frontal cortex which is involved in visual imagery, recognising future consequences, and making 'good' or 'bad' decisions.
    Supporting Study: Kasamatsu and Hirai (1999) aimed to investigate how sensory deprivation affects the brain and to investigate the role of serotonin on behaviour. They studied a group of Buddhist monks who went on a 72-hour pilgrimage to a holy Japanese mountain. On this pilgrimage, the monks were deprived of food, water, sleep, they did not talk, and they were in a cold environment. The researchers took blood samples before the monks ascended the mountain, and after they descended the mountain. Also, after about 48 hours, the monks reported that they began to hallucinate images of their ancient ancestors or feeling their presence. The researchers also took blood tests immediately after the reported hallucinations, and they found that there was an increased level of serotonin.
    Supporting Study: Higley et al. (1996) aimed to test if serotonin was related to taking risks. A field study was conducted where the researchers followed male monkeys who were migrating to new social groups. They measured the levels of serotonin by extracting cerebrospinal fluid by placing needles in their spines. The monkeys were divided into high, mid-high, mid-low, and low serotonin groups, and they were observed for how aggressive they were, the number of scars they had, and whether or not the monkeys died. It was found that 11 out of 49 monkeys who died had low serotonin levels. The researchers concluded that monkeys with low levels of serotonin are more likely to take risks like fighting with other monkeys.
    Supporting Study: Westergaard et al. (1999) aimed to test if serotonin was related to taking risks in females. The researchers conducted an observational study of captive rhesus monkeys or pigtailed macaques. The rhesus monkeys are commonly aggressive, whereas, the pigtailed macaques are usually friendly. They measured the levels of serotonin by extracting cerebrospinal fluid by placing needles in their spines. The monkeys were observed for how aggressive they behaved, and how many wounds they had. The monkeys were placed in same-sex groups, and their behaviour was observed by the researchers. It was found that rhesus monkeys were more aggressive, and they had more wounds. Additionally, the rhesus monkeys had lower levels of serotonin than the pigtailed macaques. Hence, the researchers concluded that serotonin inhibits risky behaviour in females as well as males.
    Supporting Study: Long et al. (2009) aimed to test if serotonin levels are related to gambling risks in a controlled environment. The researchers manipulated three monkeys' serotonin levels by forcing them to eat a particular diet. The monkeys were given a diet of either high tryptophan (raw material that produces serotonin) or low tryptophan. The monkeys were given a gambling task whereby they could choose a safe option which would guarantee that they would receive a fixed reward (normal amount of juice). There was also a riskier option where the monkeys could either win a higher amount of juice, or if they lost they would receive less juice. It was found that the low tryptophan group tended to chose the riskier option, whereas the high tryptophan group would choose the safer option. Long et al. concluded that the levels of tryptophan can affect serotonin levels, which in turn affects the willingness to take risks.

### Functions

Therefore, the functions of serotonin are controlling:
* mood regulation
* emotion
* appetite
* sensory perception
* sleep
* arousal levels
* temperature regulation

### Behaviours

The human behaviour is a changed perception of the environment, risk taking, and assessment of risk.

## Norepinephrine

    Supporting Study: Janowsky et al. (1972) aimed to investigate the effects of decreased norepinephrine on depression. The participants were given physostigmine (a drug that lowers levels of norepinephrine). Within minutes of taking the drug, participants' mood became depressed, and they experienced thoughts of self-hate and suicidal ideation. The researchers concluded that depression might be associated with a disturbance in norepinephrine levels. This research is supported by effective drug therapies that work to increase norepinephrine levels in depressed patients.

### Functions

Therefore, the functions of norepinephrine are:
* fight or flight response
* increases brain's oxygen levels (think clearly)
* increases glucose (or sugar) release (lets muscles work faster or harder)
* increases breathing rate (more oxygen throughout body)
* shuts down metabolic processes (focus goes to survival functions)

### Behaviours

The human behaviour is depression.

## Example response

There is no example response yet for this outcome.

## Additional Notes

There are no additional notes yet for this outcome.

# PB4

Using one or more examples, explain functions of two hormones in human behaviour
The command term explain is a level two command term, and is asking you to give a detailed account including reasons or causes. This outcome cannot be asked in an essay form and is therefore worth 8 marks.
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Hormones travel through the bloodstream to target cells to alter behaviour and are therefore slower-acting than neurotransmitters. They are produced and secreted by glands in the Endocrine System. There are several hormones:
* Cortisol
* Oxytocin
* Melatonin
* Testosterone
* Oestrogen

## Cortisol

Cortisol is a hormone which is released by the adrenal glands. Cortisol's main functions relate to regulating the stress response during fight or flight. It does this by maintaining homeostasis (maintaining a constant internal balance in response to environmental change), through regulating blood pressure, blood sugar levels, body temperature, and the cardiovascular system. All of these functions aid in the human behaviour of coping with stress because the release of cortisol enables the individual to have energy (blood sugar), breath properly (cardiovascular), reduce anxiety and think clearly (lower blood pressure) in the face of a stressful situation.
Cortisol can aid attention and concentration when released in small amounts. However, when secreted in large amounts (i.e. the body is in a serious state of stress) cortisol is attempting to restore balance in the body and to systems in order to ensure survival. As memory is a non-essential survival system it is neglected and the memory process is negatively impacted, decreasing performance. Chronic stress (prolonged cortisol release) causes atrophy in the hippocampus, permanently impacting memory.
    Supporting Study: Newcomer et al. (1999) aimed to investigate how levels of cortisol interfere with verbal declarative memory. 52 normal and healthy participants aged between 18 and 30 self-nominated themselves through a recruiting advertisement. The experiment was double bind and the participants were sorted randomly into three groups. The first group was administered 160 mg of cortisol per day, which is equivalent to cortisol levels in the blood as a consequence of a major stressful event. The second group was administered a tablet with 40 mg per day, equal to cortisol levels in the blood as a consequence of a minor stressful event. Finally, the third group was given a placebo tablet. The tablets were taken for 4 days and then the participants were given a verbal declarative memory test. The results of the test were that the first group (160 mg) performed worse than the second group (40 mg) and the third group (placebo). Furthermore, the second group showed no memory decrease. This suggests that there is a relationship between the amount of cortisol in the body and the ability to perform well on a verbal declarative memory test, whereby the higher the levels of cortisol, the poorer the performance on the memory test.
    Supporting Study: Fernald and Gunner (2008) was a field study which examined 324 boys and 315 girls aged between 2.5 and 6 (mean age =3.63) who lived in the less than 20th percentile low-income areas of urban Mexico, which were identified in a house-to-house survey. A depression scale was administered to the mothers of all of the children by the centre for epidemiological studies. Salivary cortisol samples were taken in the children to measure their hypothalamic-pituitary-adrenocortical (HPA) system activity at the time of arrival of the researchers (Time 0), 25 minutes after arrival (Time 1), and 50 minutes after arrival (Time 2). The children were administered several cognitive tests between Time 0 and Time 1. A hierarchical linear modelling analyses was used to examine the results. It was found that higher levels of maternal depressive symptoms of the mothers were associated with lower baseline cortisol levels in their children (p < 0.05), while controlling for age, gender, and time since awakening. Additionally higher levels of maternal depressive symptoms were associated with less of an increase in salivary cortisol upon the arrival of the experimenters and subsequent cognitive testing (p < 0.05). All results were moderated by gender, with enhanced cortisol response in girls and no response in boys.
    Further Reading: Robert Sapolsky is an American neuroendocrinologist who has done extensive studies on the long-term effects of Cortisol.

### Functions

Therefore, the functions of cortisol are regulating:
* blood pressure
* blood sugar levels
* body temperature
* the cardiovascular system

### Behaviours

The human behaviour is coping with stress and/or performance (on a memory test).

## Oxytocin

The hormone, oxytocin, is released by the pituitary gland, located in the hypothalamus. The functions of oxytocin include maternal bonding, milk production, uterine contractions during labour, sexual pleasure, reduced fear, and love. As a result of oxytocin providing a greater degree of love between people, in addition to the lack of fear, it instills a trusting behaviour.
    Supporting Study: Baumgartner et al. (2008) aimed to investigate the role of oxytocin after breaches of trust in a trust game. 49 participants engaged in a game used to study social interaction. Two participants played the game at one time. There was an investor (player 1) who received a sum of money and had to then choose whether to share it with a trustee (player 2) or not. If the investor shared the money, then it would triple in value. Next, the trustee must decide whether or not to share this money, or if he/she will keep it. A shared sum would indicate a trusting behaviour, whereas if the sum was kept it would indicate a violation of trust. fMRI scans were carried out on all participants and they received either oxytocin or placebo via a nasal spray. Participants played against different trustees in the trust game and also against a computer in a risk game. Their trust was broken in 50% of the games. During the game, the participants received feedback from the experimenters. The participants from the placebo group were likely to display less trust after receiving feedback on betrayal, which was demonstrated by them investing less. Alternatively participants in the oxytocin group continued to invest at similar rates after receiving feedback on a breach of trust. The fMRI scans showed decreases in responses in the amygdala and the caudate nucleus. The amygdala is involved in emotional processing and has many oxytocin receptors. The caudate nucleus is associated with learning and memory and plays a role in reward-related responses and learning to trust. In conclusion, oxytocin is suggested to play a role in trust building. Oxytocin could explain why people are able to restore trust and forgive in long-term relationships. Scanner research is merely mapping brain activity but nothing definite can be said about what it really means at this point in science.

### Functions

The functions of Oxytocin are:
* maternal bonding
* milk production
* uterine contractions
* sexual pleasure
* reduced fear
* love

### Behaviours

The human behaviour that is associated with oxytocin is trust.

## Melatonin

Melatonin controls the sleep cycle. For example, when traveling, melatonin cycles cause jet lag as the cycle does not catch up immediately to the body’s location.

## Example response

There is no example response yet for this outcome.

## Additional Notes

Memory is not classified as a human behaviour in IB (it is a mental process), so do not say it is when describing cortisol, the human behaviour is coping with stress and/or performance.

# PB5

Discuss two effects of the environment on physiological processes.
The command term discuss is a level three command term, and is asking you to offer a considered and balanced review that includes a range of arguments, factors or hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate evidence. This outcome is an essay and is therefore worth 22 marks, although it can be asked as an 8 mark.

## Example response

There is no example response yet for this outcome.

## Additional Notes

There are no additional notes yet for this outcome.

# PB6

Examine one interaction between cognition and physiology in terms of behaviour. Evaluate two relevant studies.
The command term examine is a level three command term, and is asking you to consider an argument or concept in a way that uncovers the assumptions and interrelationships of the issue. The other command term evaluate is a level three command term, and is asking you to make an appraisal by weighing up the strengths and limitations. This outcome is an essay and is therefore worth 22 marks, although it can be asked as an 8 mark.

## Example response

There is no example response yet for this outcome.

## Additional Notes

There are no additional notes yet for this outcome.

# PB7

Discuss the use of brain imaging technologies in investigating the relationship between biological factors and behaviour.
The command term discuss is a level three command term, and is asking you to offer a considered and balanced review that includes a range of arguments, factors or hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate evidence. This outcome is an essay and is therefore worth 22 marks, although it can be asked as an 8 mark.
Brain imaging technologies (BITs) are tools that provide visual images of activity in the brain. BITs are divided into two forms: structural, which refers to a still image of the brain, and functional, which monitor activity over time.

## Structural

A structural BIT is one that captures a still image of the brain. Examples of structural BITs are:
* MRI

### MRI

Magnetic Resonance Imaging (MRI) scans are used to construct a still 3D image representation of brain structures. This is done by creating a strong magnetic field by passing an electric current through wire loops. Other coils in the magnet also send and receive radio waves. This triggers protons in the water molecules in the body to align. Once aligned, radio waves are absorbed by the protons, which stimulate spinning. Energy is released after "exciting" the molecules, which in turn emits energy signals that are picked up by the coil. This information is then sent to a computer which processes all the signals and generates it into an image.
MRIs can be used in order to identify the density and volume of different brain structures. As a result of different brain structures having particular behaviours associated with them, MRIs can be used to identify human behaviour by viewing the changes in brain structures. For example, the human behaviour of neuroplasticity can be associated with changes in the volume and density of brain structures in response to environmental demands.
    Supporting Study: Maguire et al. (2000) was a quasi-experiment which investigated whether changes could be detected in the brains of London taxi drivers and to further investigate the functions of the hippocampus in spatial memory. 16 healthy male London taxi drivers were compared to 50 healthy right-handed males who did not drive taxis. The results were gathered using an MRI scan and the results were measured through Voxel Based Morphometry (VBM) and pixel counting. The first main findings of the research was that the posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects and that the anterior hippocampal region was larger in control subjects than in taxi drivers. The second main finding was that hippocampal volume correlated with the amount of time spent as a taxi driver (positively in the right posterior and negatively in the right anterior hippocampus). Maguire et al. argued that this study demonstrates the plasticity of the hippocampus in response to environmental demands.
In Maguire et al., the human behaviour of neuroplasticity is shown through the increased density and volume of the posterior hippocampus. This particular structure has an association with spatial memory, and therefore as a result of the necessity for the taxi drivers to have a better spatial memory, this structure was larger.

#### Strengths of MRI

The strengths of using an MRI are that it:
* is non-invasive
* provides images that can be used to identify damaged regions
* is reasonably fast (about 15 minutes)
* can be used to distinguish between old and new brain damage
* has no radioactive element involved (unlike PET scans)

#### Limitations of MRI

The limitations of using an MRI are that it:
* puts the participant in a noisy environment
* cannot be used to test patients that have metal in their body, such as pacemakers
* can be inaccurate
* is expensive
* does not show activity levels
* cannot actively see inside subcortical regions

## Functional

A functional BIT monitors brain activity over time. Examples of structural BITs are:
* fMRI
* PET

### fMRI

Functional Magnetic Resonance Imaging (fMRI) scans are used to measure brain activity. The scanner monitors activity by detecting the ratio of oxygenated to deoxygenated haemoglobin in blood. Haemoglobin in blood picks up oxygen from the lungs and transports it about the body. When blood passes through an active area of brain the blood flow increases due to cell activity but the brain tissue cannot soak up all the extra oxygen. This means that blood leaving an active area actually contains a larger proportion of oxygenated haemoglobin.
Through using an fMRI, it can be seen that a lack or a boost in response from a particular brain structure will result in the behaviour that is inherently associated with that structure.
    Supporting Study: Baumgartner et al. (2008) aimed to investigate the role of oxytocin after breaches of trust in a trust game. 49 participants engaged in a game used to study social interaction. Two participants played the game at one time. There was an investor (player 1) who received a sum of money and had to then choose whether to share it with a trustee (player 2) or not. If the investor shared the money, then it would triple in value. Next, the trustee must decide whether or not to share this money, or if he/she will keep it. A shared sum would indicate a trusting behaviour, whereas if the sum was kept it would indicate a violation of trust. fMRI scans were carried out on all participants and they received either oxytocin or placebo via a nasal spray. Participants played against different trustees in the trust game and also against a computer in a risk game. Their trust was broken in 50% of the games. During the game, the participants received feedback from the experimenters. The participants from the placebo group were likely to display less trust after receiving feedback on betrayal, which was demonstrated by them investing less. Alternatively participants in the oxytocin group continued to invest at similar rates after receiving feedback on a breach of trust. The fMRI scans showed decreases in responses in the amygdala and the caudate nucleus. The amygdala is involved in emotional processing and has many oxytocin receptors. The caudate nucleus is associated with learning and memory and plays a role in reward-related responses and learning to trust. In conclusion, oxytocin is suggested to play a role in trust building. Oxytocin could explain why people are able to restore trust and forgive in long-term relationships. Scanner research is merely mapping brain activity but nothing definite can be said about what it really means at this point in science.
In Baumgartner et al. fMRIs can be used to identify a lack of response in the caudate nucleus and the amygdala, which are associated with the human behaviour 'trust'. There was a reduced response in the participants whose trust was broken.

#### Strengths of fMRI

The strengths of using an fMRI are that it:
* is non-invasive
* provides accurate images of the brain in action
* can acquire repeated recordings from a single individual
* can identify the involvement of specific areas in behaviours with great accuracy
* is cheaper than PET
* can be used to investigate a wide range of sensory experiences
* has methods that have been found to enable participants to interact with a variety of displays while being scanned
* has no radioactive element involved (unlike PET scans)
* has high resolution, making it more precise than PET, with better localisation
* it a simple procedure to carry out
* allows for the active brain to be viewed, dynamic not static
* is more flexible than MRI
* can compare experimental and control conditions

#### Limitations of fMRI

The limitations of using an fMRI are that it:
* requires data from several participants must be added together to give a reliable image, and adjustments must be made for different head sizes when combining participants’ data
* requires participant cooperation
* is not a natural environment
* has a very strong magnetic field

### PET

Positron Emission Tomography (PET) scans are used to identify active areas of the brain. Participants are either injected with or drink a substance, such as glucose, which circulates throughout the body, including the brain. The glucose is first 'labelled' so that it can be detected. This is done by attaching a radioactive chemical to each molecule of glucose. As areas of the brain become active, they absorb more glucose, which is detected through the machine.
This can be used to identify behaviours because the areas of the brain that are more active will have a behaviour associated with them, as is suggested by the theory of localisation. Hence, areas that are active will indicate that a certain behaviour is being triggered, while areas that are inactive will suggest that another behaviour is not being exhibited.
    Supporting Study: The aim of Mosconi et al. (2005) was to find the earliest signs of Alzheimer’s disease in the brain. The researchers monitored 53 normal healthy participants for 9 to 24 years. The participants were scanned with a PET scanner in order to measure their metabolic rates. It was found that the participants who had shown early signs of a reduced metabolic rate in the hippocampus were associated with later development of Alzheimer's disease.
Mosconi et al. shows that through the use of PET scans, it is possible to find the relationship between particular brain structures and behaviour because the brain structure associated with the behaviour 'forgetting' is the hippocampus. When this became inactive (reduced metabolism), it led to a later development of Alzheimer's, a disease associated with memory loss (forgetting).

#### Strengths of PET

The strengths of using an PET are that it:
* is non-invasive (despite the radioactive element because it decays)
* provides accurate images of the brain in action
* can identify the involvement of specific areas in behaviour with great accuracy
* can be used to diagnose tumours
* can compare brain differences in 'normal' people to those with psychological disorders
* records ongoing activity in the brain, such as thinking

#### Limitations of PET

The limitations of using an PET are that it:
* requires data to be added together from several participants to give a reliable image, and adjustments must be made for different head sizes when combining participants’ data
* requires participant cooperation is necessary
* does not reveal fine detail
* is very expensive
* cannot be used for longitudinal studies due to the presence of the radiation
* must be used to monitor short tasks because of the rapid decay of the radioactive glucose
* can bring about possible allergies

## Example response

There is no example response yet for this outcome.

## Additional Notes

It is strongly suggested that, if you are not restricted in the amount of BITs to one, that you do at least one structural and one functional. Furthermore, if you choose to only do two, or if you are restricted to such, then it is recommended that you do not choose two under the MRI category (MRI and fMRI).