Biopsychology (A-level)

Question 1

What is localisation of function?

Answer 1

The idea that certain functions, like language and memory, have certain locations within the brain.

Question 2

Outline the motor area

Answer 2

• frontal lobe
• responsible for voluntary movements by sending signals to the muscles in the body
• both hemispheres have a motor cortex, with the motor cone on one side controlling the muscles on the opposite side of the body

Question 3

Outline the somato-sensory area

Answer 3

• parietal lobe
• receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature etc
• different parts receive messages from different locations of the body
• both hemispheres

Question 4

Outline the visual area

Answer 4

• occipital lobe
• receives and processes visual information
• the visual area contains different parts that process different types of information, including colour, shape, or movement
• both hemispheres

Question 5

Outline the auditory area

Answer 5

• temporal lobe
• responsible for analysing and processing acoustic information
• the auditory area contains different parts, and the primary auditory area is involved in processing simple features of sound including loudness, tempo, and pitch
• both hemispheres

Question 6

Outline Broca’s area

Answer 6

• left frontal lobe
• responsible for speech and language production
• left hemisphere only
• if there is damage to Broca’s area, patients can understand language but not speak

Question 7

Outline Wernicke’s area

Answer 7

• left temporal lobe
• responsible for language comprehension
• left hemisphere only
• if there is damage to Wernicke’s area, patients can speak but not understand language

Question 8

What does damage to Broca’s area cause?

Answer 8

Broca’s aphasia, characterised by speech that is slow, laborious, and lacking in fluency

Question 9

What does damage to Wernicke’s area cause?

Answer 9

Wernicke’s aphasia, when patients produce nonsense words (neologisms) as part of the content of their speech

Question 10

Localisation versus holistic theory

Answer 10

It is due to the work of Broca and Wernicke along with cases such as Phineas Gage that views of the brain changed during the 19th century. Before this time, people believed that all parts of the brain were involved in the processing of thought and action - the holistic theory of the brain. Broca and Wernicke argued for localisation of function (also called cortical specialisation). This is the idea that different parts of the brain perform different tasks and are involved with different parts of the body. It follows that if a certain area of the brain becomes damaged through illness or injury, the function associated with that area will also be affected.

Question 11

What is hemispheric lateralisation?

Answer 11

Hemispheric lateralisation is the idea that the 2 halves of the brain are functionally different and each hemisphere has functional specialisation. For example, the left is dominant for language and the right excels at visual motor tasks.

Question 12

Outline the hemispheres and the cerebral cortex

Answer 12

• The brain is divided into two symmetrical halves called the left and right hemispheres
• Some functions are dominated by one hemisphere (lateralisation)
• Activity on the left side of the body is controlled by the right hemisphere and vice versa
• The outer layer of both hemispheres is called the cerebral cortex, a 3 mm layer covering the inner parts of the brain
• This separates us from other animals as the cortex is developed. It appears grey - grey matter

Question 13

What are some examples of left brain functions?

Answer 13

Analytic thought
Logic
Language
Science and maths

Question 14

What are some examples of right brain functions?

Answer 14

Visual motor tasks
Holistic thought
Intuition
Creativity
Art and music

Question 15

Outline the corpus callosum

Answer 15

The two hemispheres are connected through nerve fibres called the corpus callosum which facilitate interhemispheric communication. The corpus callosum is a bundle of nerve fibres which joins the 2 halves of the brain. A commissurotomy is the division of the two hemispheres by surgery, which has occasionally been done to improve epilepsy.

Question 16

Outline Sperry and Gazzaniga’s study on hemispheric lateralisation with the use of split brain patients

Answer 16

Aim:
To examine the extent to which the two hemispheres are specialised for certain functions

• 11 participants
• All participants has a split brain operation

Method:
- The participant gazes at a fixation point on an upright translucent screen
- Slides are projected either side of the fixation points (into one visual field or the other) at a rate of one picture per 1/10 of a second
They conducted many different experiments:

Describe what you see -
- a picture was presented to the left or right visual field
LVF -> the patient couldn’t describe what was shown and often reported that nothing was present. Language is dominant in the left hemisphere.
RVF -> the patient would describe what they saw. Language is dominant in the left hemisphere.

Tactile tests -
- an object was placed in the left or right hand
LVF -> the patient couldn’t describe what they felt and could only make wild guesses. However, the left hand could identify an object by selecting a similar appropriate object from a series of alternate objects
RVF -> the patient could describe what they felt verbally, and could identify an object presented in the right hand by selecting a similar appropriate object from a series of alternate objects

Drawing tasks -
- a picture was presented to the left or right visual field, and the participant was asked to draw what they saw
LVF -> the left-hand would consistently draw clearer and better pictures than the right hand, even though all the participants were right-handed. This demonstrates the superiority of the right hemisphere when it comes to visual motor tasks
RVF -> the right hand would attempt to draw a picture, but the picture was never as clear as the left hand. This demonstrates the superiority of the right hemisphere for visual motor tasks

Composite words -
- a word such as keyring would flash up, with key presented to the left visual field and ring presented to the right visual field
LVF -> the participant sees key with the LVF so picks out a key with left hand
RVF -> the participant spells ring with their right hand, and says ring

Face recognition -
- the LVF sees half of a female face, while the RVF sees half of a male face
LVF -> if a split brain patient was asked to pick out a matching photo of what they had seen, they are more likely to pick out an image of a woman, as the right hemisphere deals with face recognition more, and the women’s image is processed by the right hemisphere
RVF -> if the participant was asked to name whether they had seen a man or a woman, they would be more likely to say man, as the left hemisphere deals with language and the male side of the face was processed by the left hemisphere

Conclusions:
- Information presented in one visual field is only remembered if it’s presented again to the same visual field, because only that one hemisphere has seen it; the other one can’t recognise it because it’s never seen it before
- It seems that one half of the brain does not know what the other half is doing
- Participants seem to have two separate streams of consciousness with their own memories and perceptions
- Hemispheres do seem to have different functions

Question 17

What is brain plasticity?

Answer 17

Brain plasticity refers to the brain’s ability to change and adapt because of experience.

Question 18

Outline pruning and bridging in relation to brain plasticity

Answer 18

Pruning – where connections are lost due to lack of use
Bridging – when new connections are created due to use and new stimulus

Question 19

Research on video games

Answer 19

• Kuhn (2014) got participants to play Super Mario for at least 30 minutes per day over a two month period. They then compared their brain development to a control group who were not playing video games over that two-month period
• They found significant differences in the grey matter of the video gaming participants, particularly in the cortex, hippocampus, and cerebellum
• The cerebellum is involved in coordination and movement

Question 20

Research on meditation

Answer 20

• Davidson et al (2004) studied Tibetan monks and compared them to non-meditation controls (Tibetan monks practice meditation frequently, so they make a good research sample)
• Each group was asked to meditate for a short period of time, and they were fitted with electrical sensors to detect brain activity
• The monk group showed significantly higher levels of gamma wave activity (gamma helps to coordinate neuron activity)

Question 21

What is functional recovery?

Answer 21

Functional recovery is the transfer of functions from a damaged area of the brain after trauma to other undamaged areas. We can do this through a process termed neuronal unmasking, where ‘dormant’ synapses (which have not received enough input to be active) open connections to compensate for nearby damaged areas of the brain.

Question 22

Outline functional recovery of the brain after trauma

Answer 22

• Following physical injury or trauma such stroke, affected areas of the brain are often able to adapt and compensate for those areas that are damaged
• The functional recovery that may occur in the brain after trauma is another example of neural plasticity
• Healthy brain areas may take over the functions of those areas that are damaged, destroyed, or even missing
• Neuroscientists suggest that this process can occur quickly after trauma (spontaneous recovery) and then slow down after several weeks or months. At this point, the individual may need rehabilitative therapy.

Question 23

What happens to the brain during recovery?

Answer 23

• The brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage
• Secondary neural pathways that would not typically be used to carry out certain functions are activated or ‘unmasked’ to enable functioning to continue, often in the same ways as before
• This process is supported by a number of structural changes in the brain

Question 24

What are the three structural changes in the brain during recovery?

Answer 24

Axonal sprouting
Reformation of brain vessels
Recruitment of homologous areas

Question 25

What is axonal sprouting?

Answer 25

Axonal sprouting is the growth of new nerve endings which connect with other undamaged nerve cells to form new neural pathways.

Question 26

What is recruitment of homologous areas?

Answer 26

• This is when a homologous (similar) area of the brain on the opposite side is used to perform a specific task
• One example would be if Broca’s area was damaged, the right sided equivalent would carry out its functions
• After a period of time, functionality may then shift back to the left side

Question 27

What is reformation of blood vessels?

Answer 27

With neural pathways, this is supporting and reinforcing those new neural pathways with blood vessels

Question 28

Outline Functional Magnetic Resonance Imaging (fMRI)

Answer 28

• Functional MRI measures blood flow in the brain when a person performs a task
• Neurons in the brain that are the most active use the most energy
• Energy requires glucose and oxygen
• Oxygen is released for use by these active neurons, at which point haemoglobin (which carries the oxygen) becomes deoxygenated
• Deoxygenated haemoglobin has a different magnetic quality from oxygenated haemoglobin and an fMRI can detect these different magnetic qualities to create a dynamic 3D map of the brain
• An fMRI is non-invasive
• It shows activity approximately 1-4 seconds after it occurs
• It’s accurate within 1-2 mm
• fMRI scans don’t provide a direct measure of neural activity, they simply measure changes in blood flow, meaning you can’t prove causation

Question 29

Outline electroencephalograms (EEG)

Answer 29

• EEG scanners measure electrical activity through electrodes attached to the scalp
• Information is processed in the brain as electrical activity in the form of action potentials or nerve impulses
• Small electrical charges are detected by the electrodes and graphed over a period of time, indicating the level of activity
• There are four types of EEG patterns: alpha, beta, theta, and delta waves
• EEG patterns produce two distinctive states: synchronised and desynchronised patterns
• Synchronised patterns or a recognisable wave form (alpha, beta, delta, or theta)
• Desynchronised is no pattern
• EEG can also be used to detect illnesses like epilepsy and sleep disorders and to diagnose other disorders that affect brain activity like Alzheimer’s disease
• EEGs are non-invasive
• They show activity every millisecond, recording activity in nearly real time
• They only detect activity in superficial, general areas of the brain
• Electrical activity is often detected in several regions, and it can be difficult to pinpoint the exact region of activity, meaning you can’t prove causation

Question 30

Outline Event-Related Potentials (ERP)

Answer 30

• ERPs use similar equipment to EEG (electrodes attached to the scalp)
• Stimulus is presented to a participant, for example a picture/sound, and the researcher looks for activity related to that stimulus
• The stimulus is presented many times, usually hundreds, and an average response is graphed
• The time or interval between the presentation of the stimulus and the response is referred to as latency
• ERPs that occur after 100 ms are referred to as cognitive ERPs
• ERPs that occur within 100 ms are referred to as sensory ERPs
• ERPs are non-invasive
• They show activity every millisecond (1-10 ms)
• They only detect activity in superficial, general areas of the brain
• ERPs enable the determination of how processing is affected by a specific experimental manipulation so show causation

Question 31

Outline Post-Mortem Examination

Answer 31

• Researchers study the physical brain of a person who displayed a particular behaviour while they were alive
• Examples include Broca and Wernicke
• Post-mortems have contributed to our understanding of many disorders
• Iverson examined the brains of deceased schizophrenic patients. He found a higher concentration of dopamine, especially in the limbic system, compared to non-schizophrenics.
• Post-mortem studies allow for a more detailed examination of anatomical and neurochemical aspects of the brain then would be possible with other techniques
• Post-mortems non-invasive, as the patient is dead
• The deficit a patient displays during their lifetime, e.g. an inability to speak, may not be linked to the deficits found in the brain, e.g. a damaged Broca’s area, so you can’t establish causation

Question 32

What is spatial resolution?

Answer 32

Spatial resolution refers to the smallest feature or measurement that a scanner can detect, and is an important feature of brain scanning techniques.

Question 33

What is temporal resolution?

Answer 33

Temporal resolution refers to the accuracy of the scanner in relation to time, or how quickly the scanner can detect changes in brain activity.

Question 34

What are biological rhythms?

Answer 34

Biological rhythms are cyclical patterns within biological systems that have evolved in response to environmental influences e.g. day and night. There are two key factors that govern biological rhythms which are endogenous pacemakers (internal), the bodies biological clocks, and exogenous zeitgebers (external), which are changes in the environment.

Question 35

Outline circadian rhythms

Answer 35

• A type of biological rhythm that operates along a 24-hour cycle
• This regulates a number of bodily processes, such as the sleep/wake cycle, core body temperature, and hormone production

Question 36

Outline the sleep/wake cycle

Answer 36

• Light provides the primary input to this system
• Light is first detected by the eye, which then sends messages, in relation to brightness, to the suprachiasmatic nuclei (SCN)
• The SCN then uses this information to coordinate the activity of the entire circadian system
• Sleeping and wakefulness are not determined by the circadian rhythm alone, but also by homeostasis
• The brains circadian clock regulates sleeping and feeding patterns, alertness, core body temperature, brainwave activity, hormone production, regulation of glucose and insulin levels, urine production, cell regeneration, and many other biological activities
• The most important hormones affected by the circadian clock, at least in so far as they affect sleep, are melatonin, which is produced in the pineal gland in the brain, and which chemically causes drowsiness and lowest body temperature, and cortisol, which is produced in the adrenal gland and used to form glucose or blood sugar, and to enable anti-stress and anti-inflammatory functions in the body
• Physically, the circadian clock is located in the suprachiasmatic nucleus (SCN) in the hypothalamus of the brain, one in each brain hemisphere
• The SCN is a tiny pinhead sized area containing just 20,000 or so very small neurons, but it has the responsibility for sending signals to several other parts of the brain to regulate the daily sleep/wake cycle, body temperature, hormone production and other functions
• Core temperature usually reaches its minimum around four thirty to five a.m. in the morning in human adults and melatonin typically begins to be produced around eight to nine p.m. at night and stops around seven to eight a.m. in the morning
• The deepest tendency to sleepiness occurs in the middle of the night, around 2 to 3 am, along with a shorter and shallower period of sleepiness, often referred to as the post lunch dip, about 12 hours after around 2 to 3 pm in the afternoon

Question 37

Outline Aschoff and Wever’s study and Folkard et al’s study on circadian rhythms.

Answer 37

Aschoff and Wever convinced a group of participants to spend four weeks in a World War II bunker deprived of natural light. All but one of the participants (who’s sleep wake cycle extended to 29 hours) displayed a circadian rhythm between 24 and 25 hours. Both Siffre’s experience and the bunker study suggests that the natural sleep wake cycle may be slightly longer than 24 hours, but that it is entrained by exogenous zeitgebers associated with our 24 hour day such as the number of daylight hours and typical meal times.

Folkard et al studied a group of 12 people who agreed to live in a dark cave for three weeks, retiring to bed when the clock said 11:45 and rising when it said 7:45. Over the course of the study, the researchers gradually sped up the clock, unbeknown to the participants, so an apparent 24 day eventually lasted only 22 hours. It was revealed that only one of the participants was able to comfortably adjust to the new regime, suggesting the existence of a strong, free running circadian rhythm that cannot easily be overridden by exogenous zeitgebers.

Question 38

Outline Siffre’s cave study

Answer 38

Michael Siffre spent several extended periods underground to study the effects of his own biological rhythms. Deprived of exposure to natural light and sound, Siffre resurfaced from caves in mid September, after two months in the caves, believing it to be mid August. This shows that the absence of external cues significantly altered his circadian rhythm, suggesting that his 24 hour sleep wake cycle was increased by the lack of external cues, making him believe one day was longer than it was. He repeated this again and each time he found his free running biological rhythm settled down to one that was around 25 hours, although he continued to fall asleep and wake up on a regular schedule.

Question 39

What are infradian rhythms?

Answer 39

Infradian rhythms last longer than 24 hours and can be weekly, monthly, or annually.
Examples include the menstrual cycle, seasonal affective disorder, and hibernation in animals

Question 40

What are ultradian rhythms?

Answer 40

Ultradian rhythms last fewer than 24 hours. Examples include human sleep patterns and meal patterns.

Question 41

Outline examples of infradian rhythms

Answer 41

The menstrual cycle is governed by monthly changes in hormone levels, which regulate ovulation. The cycle refers to the time between the first day of a woman’s period, when the womb lining is shed, to the day before her next period. The typical cycle takes approximately 28 days although can be anywhere between 23 and 36 days. During each cycle, rising levels of oestrogen cause the ovary to develop an egg and release it (ovulation). After ovulation, the hormone progesterone helps the womb lining to grow thicker, readying the body for pregnancy. If pregnancy does not occur, the egg is absorbed into the body and womb lining comes away and leaves the body.

Seasonal affective disorder is an infradian rhythm related to the seasons. Melatonin is secreted by the pineal gland at night and longer nights mean increased melatonin secretion, which is linked to an increase in depression symptoms.

Question 42

Outline sleep stages as an example of an ultradian rhythm

Answer 42

• Psychologists have identified five distinct stages of sleep that altogether span about 90 minutes - a cycle that continues throughout the course of the night
• Each of these stages is characterised by a different level of brainwave activity, which can be monitored using an EEG
• Stages 1 and 2 are ‘light sleep’ stages - brain patterns become slower, starting with alpha waves and progressing to theta waves
• Stage 1 is 4-5% of your sleep cycle, and stage 2 is 45 to 55%
• Stage 3 and 4 are ‘deep sleep’ or slow wave sleep stages - associated with delta waves
• Stage 3 is 4-6% of each sleep cycle, and stage 4 is 12 to 55%
• Stage 5 is REM or rapid eye-movement sleep, also known as dream sleep - the body is paralysed and brain waves are desynchronised
• REM sleep is 20 to 25% of each sleep cycle

Question 43

Outline what happens during the sleep wake cycle and other factors affecting endogenous pacemakers

Answer 43

• Low levels of light hit the retina
• Melanopsin carries signals to the SCN
• Axonal pathway to pineal gland
• Melatonin
• Induced sleep

The sensitivity of the pineal gland and SCN to light means that although these are endogenous pacemakers, their activity must be synchronised with the light/dark of the environment. Therefore, desynchronisation of the two is a problem.

Question 44

Outline endogenous pacemakers and exogenous zeitgebers

Answer 44

• Biological rhythms are regulated by endogenous pacemakers, which are the body’s internal biological clocks, and exogenous zeitgebers, which are external cues including light that help to regulate the internal biological clocks
• Endogenous pacemakers are internal mechanisms that govern biological rhythms, in particular the circadian sleep wake cycle
• Although endogenous pacemakers are internal biological clocks, they can be altered and affected by the environment
• For example, although the circadian sleep wake cycle will continue to function without natural cues from light, research suggests that light is required to reset the cycle every 24 hours

Question 45

Outline the main endogenous pacemakers

Answer 45

In mammals, the main endogenous pacemaker is a pair of tiny clusters of nerve cells called the SCN which lie in the hypothalamus, just above the optic chiasm.

Even when our eyes are shut, the SCN gets info on light from the optic nerve. Light can penetrate the eyelids and special photoreceptors in the eye transfer light signals to the SCN. If our endogenous clock is running slow, the morning light automatically shifts the clock ahead, so it is in synchrony with the world outside.

The pineal gland is another endogenous pacemaker that works with the SCN. The pineal gland contains light sensitive cells. When light is sensed, melatonin production is inhibited. When light level falls, melatonin production increases, which induces sleep by inhibiting brain mechanisms that promote the awake state.

Light, the pineal gland, and melatonin regulate the sleep wake cycle.

Question 46

Outline exogenous zeitgebers

Answer 46

• The biological clock is reset each day by cues in the environment, like the light cues of sunrise and sunset
• This process is called entrainment, which is the opposite of free running, where the biological clock works free of any exogenous cues, including social cues like clocks
• Exogenous zeitgebers can be described as environmental events that are responsible for resetting the biological clock of an organism
• These include social cues, such as mealtimes, and light, which is responsible for resetting the body clock each day, keeping it on a 24 hour cycle

Question 47

Evaluate localisation of function in the brain

Answer 47

A limitation of localisation of function is some psychologists argue that the idea of localisation fails to take into account individual differences. Herasty found that women have proportionally larger Broca’s and Wenicke’s areas than men, which can perhaps explain the greater ease of language use among women. This however suggests a level of beta bias in the theory, as the differences between men and women are ignored and variations in the pattern of activation and the size of areas observed during various language activities are not considered. Therefore, we are unable to generalise research examining localisation of function to males and females equally, as the different brain structures suggest that different considerations are required when considering the different sexes.

The claim that functions are localised to certain areas of the brain has been criticised. Lashley proposed the equipotentiality theory, which suggests that the basic motor and sensory functions are localised, but the higher mental functions are not. He claims that intact areas of the cortex could take over responsibility for specific cognitive functions following brain injury. Critics like Lashley argue that theories of localisation are biologically reductionist in nature and try to reduce very complex human behaviours and cognitive processes to one specific brain region. Such critics suggest that a more thorough understanding of the brain is required to truly understand complex cognitive processes like language. This therefore casts doubt on theories about the localisation of functions, suggesting that functions are not localised to just one region, as other regions can take over specific functions following brain injury.

A strength of localisation of function is it has been demonstrated using brain imaging techniques such as fMRI. Peterson used brain scans to demonstrate how Wernicke’s area was active during a listing task and Broca’s area was active during a reading task, suggesting these areas have different functions. Similarly, using brain scans, Tulving found that semantic and episodic memories reside in different parts of the prefrontal cortex. This suggests the different functions of the brain are localised to different areas.

A strength of localisation of function is it has research evidence support. Phineas Gage was injured in a rail road accident where a metre long iron pole entered his head through his left cheek, passed behind his left eye, and exited his brain and skull from the top of his head. Before the accident he’d been a good worker, but now he was boisterous and rude and his friend said he was ‘no longer Gage’. It can be concluded that Gage’s frontal lobes were damaged in the pre-frontal region, which accounted for his disinhibited behaviour. This supports the theory of localisation, in that personality and mood are governed by the frontal lobes and damage to these areas may cause personality changes.

Question 48

Evaluate hemispheric lateralisation and split brain research

Answer 48

One of the main advantages of brain lateralisation is that it increases neural processing capacity, or the ability to multitask. Rogers et al found that in a domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously. Using only one hemisphere to engage in a task leaves the other hemisphere free to engage in other functions. This provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in cognitive tasks. However, because this research was carried out on animals it is impossible to conclude that we can extrapolate these findings onto humans. Unfortunately, much of the research into lateralisation is flawed because the split brain procedure is rarely carried out, meaning patients are difficult to come by. Such studies often include very few participants and often the research takes an idiographic approach. Therefore, any conclusions drawn are representative only of those individuals who had a confounding physical disorder that made the procedure necessary. This is problematic, as such results cannot be generalised to the wider population.

A limitation of hemispheric lateralisation is it can be argued that language may not be restricted to the left hemisphere. Turk et al discovered a patient that suffered damage to the left hemisphere, but developed the capacity to speak in the right hemisphere, eventually leading to the ability to speak about the information presented to either side of the brain. This matter is because it suggests that perhaps lateralisation is not fixed, and that the brain can adapt following damage to certain areas.

One limitation of Sperry’s research is that causal relationships are hard to establish. The behaviour of Sperry’s brain participants was compared to a neurotypical control group. An issue though is that none of the participants in the control group had epilepsy. This is a major confounding variable as any differences that were observed between the two groups may be the result of the epilepsy rather than a split brain. This means that some of the unique features of the split brain participants’ cognitive abilities may have been due to the epilepsy not their split brain, leaving the validity of this research to question.

Lateralisation of function appears to change with normal aging. Across many types of tasks and many brain areas lateralised patterns found in younger individuals tend to switch to bilateral patterns in healthy older adults. Psychologists found that language became more lateralised to the left hemisphere with increasing age in children and adolescents, but after the age of 25 lateralisation decreases with age. This might be because using the extra processing resources of the other hemisphere may in some way compensate for age related decline in function.

Question 49

Evaluate brain plasticity and functional recovery

Answer 49

There is research is to support the notion of brain plasticity. Maguire et al found that the posterior hippocampal volume of London taxi driver’s brains was positively correlated with their time as a taxi driver, and that there were significant differences between a taxi driver’s brain, and those of control subjects. However, some psychologists suggest that research investigating the plasticity of the brain is limited. For example, Maguire’s research is biologically reductionist and only examines a single biological factor, the size of the hippocampus in relation to spatial memory. This approach is limited and fails to take into account all of the different biological/cognitive processes involved in spatial navigation which may limit our understanding. Therefore, while Maguire’s research shows that the brain can change in response to frequent exposure to a particular task, some psychologists suggest that the holistic approach to understanding complex human behaviour may be more appropriate.

A strength of research examining plasticity and functional recovery is the application of the findings to the field of neurorehabilitation. Understanding the processes of plasticity and functional recovery has led to the development of neurorehabilitation, which uses motor therapy and electrical stimulation of the brain to counter the negative effects and deficits in motor and cognitive functions following accidents, injuries, and or strokes. This matters because it demonstrates a positive application of research in this area to help improve the cognitive functions of people suffering from injuries.

There is research support for the idea of brain plasticity. Kuhn et al found a significant increase in grey matter in various regions of the brain after participants played video games for 30 minutes a day over a two month period. This matters because Kuhn provides clear evidence for brain plasticity and shows how experience can cause structural changes in the brain.

While there is evidence for functional recovery, it is possible that this ability can deteriorate with age. Elbert et al concluded that the capacity for neural reorganisation is much greater in children than adults, meaning that new regeneration is less effective in older brains. This may explain why adults find change more demanding than young people. Therefore, we must consider individual differences when assessing the likelihood of functional recovery in the brain after trauma .
A limitation of plasticity is that it may have negative behavioural consequences. Evidence has shown that the brains adaptation to prolonged drug use leads to poorer cognitive functioning in later life, as well as an increased risk of dementia. Furthermore, 60 to 80% of amputees have been known to develop phantom limb syndrome, which is the continued experience of sensations in the missing limb as if it was still there. The sensations are usually unpleasant, painful, and are thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss. This suggests that the brains ability to adapt to damage is not always beneficial.

Question 50

Evaluate circadian rhythms

Answer 50

A disadvantage of the research studies conducted without natural light is that artificial light sources may have acted as a replacement for the natural light in regulating the body clock. For example, in Siffre’s study, he turned on a lamp every time he woke up and left it on until he went to sleep. However, research from Czeisler et al showed how lighting could adjust the circadian rhythm from 22 to 28 hours by dimming the lights. It was found that the light could possibly be equivalent to the participant taking a drug resetting the biological clock. This means that the researchers didn’t take artificial lighting into account, confounding the results and making them unreliable because the true effect is unknown.

A limitation of studies into the sleep wake cycle is that they often have small samples. For example, the experiments by Ashcoff and Wever involved small groups of participants or studies of single individuals in the case of Siffre. Findings from these studies would therefore be difficult to generalise to the wider population due to lack of representativeness. Moreover, Siffre observed differences in his own body clock at the age of 60 compared to the age 36, highlighting age as a confounding variable. This suggests the studies are useful for highlighting factors which may affect our circadian rhythms, but less so for generalising from.

One strength of research into circadian rhythms is that it has practical applications for drug treatments. Research into circadian rhythms reveals that there are certain times during the day and night when drugs are more likely to be effective, which has led to the development of guidelines relating to the drug dosage and timing for many medications. This has a direct impact on the economy, as knowing how drugs are best absorbed and distributed throughout the body makes them more likely to be used effectively and efficiently. Therefore, less days will be taken off sick due to shorter cycles of medication use and more affective dosing as a result of applying the findings of this research.

One strength of research into circadian rhythms is that it provides an understanding of the adverse consequences that occur when they are disrupted (desynchronisation). For example, night workers engaged in shiftwork experience a period of reduced concentration around six in the morning, which is a circadian trough, meaning mistakes and accidents are more likely. Research has also pointed to a relationship between shiftwork and poor health; shift workers are three times more likely to develop heart disease than people who work with typical work patterns. This shows that research into the sleep wake cycle may have real world economic implications in terms of how best to manage worker productivity. However, studies investigating the effects of shift work tend to use correlational methods. This means it’s difficult to establish whether the desynchronisation of the sleep wake cycle is actually a cause of negative effects or other factors. For example a psychologist concluded that high divorce rates in shiftworkers might be due to the strain of deprived sleep and other influences such as missing out on important family events. This suggests that it may not be biological factors that create the adverse consequences associated with shift work.

There are individual differences in circadian rhythms. One is the cycle length - a psychologist found that circadian rhythms can vary from 13 to 65 hours. Also, people appear to be innately different in terms of when their circadian rhythms peak. For example, Duffy et al found that ‘morning people’ prefer to rise and go to bed early, about 6 am and 10 pm, whereas ‘evening people’ prefer to wake and go to bed later, 10 am and 1 am. Therefore, individual differences in circadian rhythms need to be taken into account.

Question 51

Evaluate infradian and ultradian rhythms

Answer 51

Support for the synchronicity of the menstrual cycle comes from McClintock. 29 women with a history of irregular periods gave samples of pheromones at different stages of the menstrual cycle. Pads were used to collect this from their armpits. These were then rubbed onto the upper lips of the other participants. 68% of women experienced changes to their cycle, bringing them closer to the cycle of their ‘odour donor’, suggesting that the menstrual cycle can be synchronised to that of other women and supporting the role of exogenous factors in the menstrual cycle. This study also provides support for the evolutionary basis of menstruation. For example, if our ancestors menstruated together, it would’ve been an evolutionary advantage. New babies would’ve been part of a social group which cared for one another, enhancing survival. This supports the synchronicity of the menstrual cycle.

Reinberg examined a woman who spent three months in a cave with only a small lamp to provide light. Reinberg noted that her menstrual cycle shortened from the usual 28 days to 25.7 days. This result suggests that the lack of light (an exogenous zeitgeber) in the cave affected her menstrual cycle, and therefore demonstrates the effect of external factors on infradian rhythms.

Randy Gardener remained awake for 264 hours. After this experience, Randy slept for only 15 hours and over several nights he recovered only 25% of his lost sleep. However, he recovered 70% of stage four sleep, 50% of his REM sleep and very little of the other stages. These results highlight the large degree of flexibility in terms of the different stages within the sleep cycle and the variable nature of this ultradian rhythm.

There is evidence to support the separate distinct sleep stages. Psychologist monitored sleep patterns of nine adult participants in a sleep lab. Brainwave activity was recorded on an EEG, and they found that REM sleep was correlated with dreaming. This suggests that REM sleep is a distinct stage in which dreaming takes place, supporting the existence of the sleep stages as an ultradian rhythm.

Question 52

Evaluate endogenous pacemakers and exogenous zeitgebers

Answer 52

There is research support for the importance of endogenous pacemakers, in particular the SCN, in relation to the sleep wake cycle. Morgan bred hamsters so that they had circadian rhythms of 20 hours rather than 24. SCN neurons from these abnormal hamsters were transplanted into the brains of normal hamsters, who subsequently displayed the same abnormal circadian rhythm of 20 hours, showing that the transplanted SCN had imposed its pattern onto the hamsters. However, this research is difficult to generalise because of its use of hamsters. Humans would respond very differently to manipulations of their biological rhythms, not only because we are different biologically but also because of the vast differences between environmental contexts. Therefore, while this research demonstrates the significance of the SCN and how endogenous pacemakers impact biological rhythms, research carried out on animals may be unable to explain the role of endogenous pacemakers on the sleep wake cycle in humans.

There is research support for the role of exogenous zeitgebers on the sleep wake cycle. When Michael Siffre returned from an underground stay with no clocks or light, he believed the date to be a month earlier than it was, which demonstrates the importance of the exogenous zeitgeber light on the sleep wake cycle. However, Siffre’s case study has been the subject of criticism. As the researcher and sole participant in his case study, there are several issues with potential researcher bias and a lack of generalisability to the wider population. Therefore, while these result suggests that the 24 hour sleep wake cycle was increased by the lack of endogenous zeitgebers, showing the impact of such factors on the bodily rhythms, these findings should be treated with caution, as we are unable to conclude whether the role of exogenous zeitgebers affect the sleep wake cycle in the wider population on the basis of this case study alone.

Despite all the research support for the role of endogenous pacemakers and exogenous zeitgebers, the argument could still be considered reductionist for overly simplifying a complex human phenomena. For example, it could be argued that the sleep wake cycle is influenced by other people and social norms i.e. sleep occurs when it’s dark because that is the social norm and it wouldn’t be socially acceptable for a person to conduct their daily routines during the night. Therefore, the research discussed could be criticised for being reductionist as it only considers a limited range of factors e.g. SCN/light and fails to consider the other widely divergent viewpoints, suggesting that our understanding of the effect of endogenous pacemakers and exogenous zeitgebers on the sleep wake cycle is limited.

A limitation of SCN research is that it may obscure other body clocks. Research has revealed that there are numerous circadian rhythms in many organs and cells in the body. These peripheral oscillators are found in the organs, including the lungs, pancreas, and skin. They are influenced by the actions of the SCN but also act independently. A psychologist demonstrated how changing feeding patterns in mice could alter the circadian rhythms of cells in the liver by up to 12 hours whilst leaving the rhythm of the SCN unaffected. This suggests other complex influences on the sleep wake cycle.