Biopsychology 🧬

Question 1

What is the Nervous System?

Answer 1

The nervous system is divided into two main components:
1) Central nervous system (CNS)
— Brain
— Spinal cord

2) The peripheral nervous system (PNS)
— Somatic nervous system
— Autonomic nervous system : sympathetic + parasympathetic

Question 2

CNS | What is the CNS?

Answer 2

The CNS consists of the brain and the spinal cord.
— The brain provides awareness and is involved in all psychological processes.
— The brain consists of many regions, which are responsible for different functions.

Question 3

CNS | What are the four main lobes of the brain and their functions?

Answer 3

> Frontal Lobe:
+ Associated with higher-order functions including planning, abstract reasoning and logic.

> Parietal Lobe:
+ Integrates information from the different senses and therefore plays an important role in spatial navigation.

> Temporal Lobe:
+ Processes auditory information

> Occipital Lobe:
+ Processes visual information

Question 4

CNS |What is the purpose of the brain stem?

Answer 4

The brain stem connects the brain and spinal cord and controls involuntary processes including out heartbeat, breathing and consciousness.

Question 5

CNS |What is the role of the spinal cord?

Answer 5

The role of the spinal cord is to transfer messages to and from the brain and the rest of the body.

The spinal cord is also responsible for simple reflect actions that do not involve the brain, for example, jumping out of your chair if you sit on something sharp.

Question 6

PNS | What is the role of the peripheral nervous system (PNS)?

Answer 6

The role of the PNS is to relay messages (nerve impulses) from the CNS (brain and spinal cord) to the rest of the body.
The PNS consists of two main components:

1) The somatic nervous system
2) The autonomic nervous system

Question 7

PNS | What role does the somatic nervous system play?

Answer 7

The somatic nervous system facilitates communication between the CNS and the outside world.

The somatic nervous system is made up of sensory receptors that carry information to the spinal cord and brain, and motor pathways that allow the brain to control movement.
— Therefore, the role of the somatic nervous system is to carry sensory information from the outside world to the brain and provide muscle responses via motor pathways.

Question 8

PNS | What is the role of the autonomic nervous system?

Answer 8

The autonomic nervous system plays an important role in homeostasis, which maintains internal processes like body temperature, heart rate and blood pressure. The autonomic nervous system only consists of motor pathways and has tow components: sympathetic nervous system and parasympathetic nervous system.

> SYMPATHETIC NERVOUS SYSTEM:
— Typically involved in responses that prepare the body for fight or flight.
— Impulses travel from the sympathetic nervous system to organs in the body to help us prepare for action when we are faced with a dangerous situation.
— Eg. heart rate, blood pressure and breathing rate increases, while the less important functions like digestion salvation and the desire to urinate are suppressed.

> PARASYMPATHETIC NERVOUS SYSTEM:
— Relaxes the body and returns us to out ‘normal’ resting state.
— Slows down our heart rate and breathing rate, and reduces our blood pressure
— Any functions that were previously slowed down during fight or flight reaction are started again (eg. digestion)

Question 9

Neurons | What are the three main types of neurons?

Answer 9

1. Sensory
2. Relay
3. Motor

Each of these have a different function depending on its location in the body and its role within the nervous system.

Question 10

Neurons | What are sensory neurons?

Answer 10

Sensory neurons are found in receptors such as the eyes, ears, tongue and skin.
— They carry nerve impulses to the spinal cord and brain.

When these nerve impulses reach the brain, they are translated into ‘sensations’ such as vision, hearing, taste and touch.
However, not all sensory neurons reach the brain as some neurons stop at the spinal cord, allowing for quick reflex actions.

Question 11

Neurons | What are relay neurons?

Answer 11

Relay neurons are found between the sensory input and motor output/response.
— They are found in the brain and spinal cord and allow sensory and motor neurons to communicate.

Question 12

Neurons | What are motor neurons?

Answer 12

Motor neurons are found in the central nervous system (CNS) and control muscle movements.
— When motor neurons are stimulated, they release neurotransmitters that bind to the receptors on muscles to trigger a response, which leads to movement.

Question 13

Neurons | What are the different parts and functions of neurons?

Answer 13

> DENDRITES:
— Receive signals from other neurons or form sensory receptor cells.
— They’re typically connected to the cell body, which is often referred to as the ‘control centre’ of the neuron, as it contains the nucleus.

> AXON:
— The axon is a long slender fibre that carries nerve impulses, in the form of an electrical signal known as an action potential, away from the cell body towards the axon terminals, where the neuron ends.
— Most axons are surrounded by a myelin sheath (except for relay neurons) which insulates the axon so that the electrical impulses travel faster along the axon.

> AXON TERMINAL:
— Connects the neuron to other neurons (or directly to organs), uing a process called synaptic transmission.

Question 14

Neurons | Explain the process of synaptic transmission.

Answer 14

1. Information is passed down the axon of the neuron as an electrical impulse - this is known as action potential.
2. Once the action potential reaches the end of the axon, it needs to be transferred to another neuron or tissue.
3. It then must cross over between the pre-synaptic neuron and post-synaptic neuron - which is known as synaptic gap.
   — At the end of the neuron (in the axon terminal) are synaptic vesicles which contain chemical messengers, known as neurotransmitters.
4. When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters.
5. Neurotransmitters then carry the signal across the synaptic gap. They bind to receptor sites on the postsynaptic cell that then becomes activated.
6. Once the receptors have been activated, they either produce excitatory ot inhibitory effects on the postsynaptic cell.

Question 15

Neurons | What is the difference between neurotransmitters that are excitatory vs inhibitory?

Answer 15

> EXCITATORY NEUROTRANSMITTERS (eg. noradrenaline):
— Make the post-synaptic cell more likely to fire.
— Eg. a neurotransmitter like noradrenaline binds to the post-synaptic receptor and it will cause an electrical charge in the cell membrane which results in excitatory postsynaptic potential (EPSP)

> INHIBITORY NEUROTRANSMITTERS (eg. GABA):
— Make them less likely to fire
— Eg. if an inhibitory neurotransmitter like GABA binds to the post-synaptic receptors, it will result in an inhibitor post-synaptic potential (IPSP) which makes the post-synaptic cell less likely to fire.

Question 16

ES | What is the Endocrine System?

Answer 16

The endocrine system works alongside the nervous system and is made up of glands and hormones.

Question 17

ES | What functions do glands have in the endocrine system?

Answer 17

It is a network of glands across the body that secrete messages called hormones.
— Instead of using nerves (sensory and motor neurons) to transmit information, this system uses blood vessels.

Some glands which make up the endocrine system are:
+ Hypothalamus
+ Thyroid and parathyroid glands
+ Thymus
+ Pancreas
+ Pineal gland
+ Pituitary gland
+ Adrenal glands
+ Ovary (females)
+ Testicle (males)

Each gland produces a different hormone.

Question 18

ES | What are the function of hormones in the endocrine system?

Answer 18

The word ‘hormone’ comes from the Greek work ‘hormao’ which means ‘excite’, as hormones excite (stimulate) a particular part of the body.

> HYPOTHALAMUS:
— Connected the the pituitary gland and is responsible for stimulating or controlling the release of hormones from the pituitary gland.
— The hypothalamus is the control system which regulates the endocrine system.

> PITUITARY GLAND:
— Sometimes known as the master gland because the hormones released by the pituitary gland control and stimulate the release of hormones from other gads in the endocrine system.
— It’s divided into the anterior (front) and posterior (rear) lobes, which release different hormones
+ POSTERIOR LOBE - a key hormone released from this lobe is oxytocin (often referred to as the ‘love hormone’ which is responsible for uterine contractions during childbirth.
+ ANTERIOR LOBE - releases the adrenocortical trophic hormone (ACTH) which stimulates the adrenal cortex and the release of cortisol during the stress response.

> PINEAL GLAND:
— Main hormone it releases is melatonin, which is responsible for important biological rhythms, including the sleep-wake cycle.

> THYROID GLAND:
— Releases thyroxine which is responsible for regulating metabolism.
— People who have a fast metabolism typically struggle to put on weight, as metabolism is involved in the chemical process of converting food into energy.

> ADRENAL GLAND:
— Divided into two parts: the adrenal medulla and the adrenal cortex.
+ ADRENAL MEDULLA - responsible for releasing adrenaline and noradrenaline, which play a key role in the fight-or-flight response.
+ ADRENAL CORTEX - releases cortisol, which stimulates the release of glucose to provide the body with energy whilst suppressing the immune system.

Question 19

ES | What glands are specific to males / females and what function do they have?

Answer 19

> TESTES:
— Release androgens, which include the main hormone testosterone.
— Testosterone is responsible for the development of male sex characteristics during puberty whilst also promoting muscle growth.

> OVARIES:
— Release oestrogen which controls the regulation of the female reproductive system, including the menstrual cycle and pregnancy.

Question 20

F/F | What is the Fight-or-Flight response?

Answer 20

When someone enters a potentially stressful situation, the amygdala is activated. The amygdala responds to sensory input (what we hear, see, smell etc.) and connects sensory input with emotions associated with the fight-or-flight response (eg. fear and anger).

If the situation is deemed stressful / dangerous, the amygdala sends a distress signal to the hypothalamus, which communicates with the body through the sympathetic nervous system. If the situation requires short-term response, the sympathomedullary pathway (SAM pathway) is activated, triggering the fight-or-flight response.

Question 21

F/F | What is the process of fight-or-flight?

Answer 21

1) A person enters a stressful / dangerous situation.

2) The amygdala is activated which sends a distress signal to the hypothalamus.

3) The hypothalamus activated the sympathomedullary pathway (SAM pathway) which is the pathway running to the adrenal medulla and the Sympathetic Nervous System.

4) The SNS stimulates the adrenal medulla (part of adrenal gland).

5) The adrenal medulla secretes adrenaline and noradrenaline into the bloodstream.

6) Adrenaline causes a number of physiological changes to prepare the body for fight-or-flight (eg. increased heart rate to increase blood flow to organs and movement of adrenaline around the body).

Question 22

F/F | What are the different physiological changes caused by adrenaline and why do they occur?

Answer 22

+ Increased heart rate - to increase blood flow to organs and increase the movement of adrenaline around the body.

+ Increased breathing rate - to increase oxygen intake.

+ Pupil dilation - to increase the amount of light entering the eye and enhance vision (especially in the dark).

+ Sweat production - to regulate temperature.

+ Reduction of non-essential functions (eg. digestive system, urination, salivation) - to increase energy for other essential functions.

Question 23

F/F | What role does the Parasympathetic Nervous System play after the individual is out of fight-or-flight?

Answer 23

Following the fight-or-flight response, the parasympathetic nervous system is activated to return the body back to its ‘normal’ resting state.

Consequently, the parasympathetic nervous system slows down our heart rate and breathing rate and reduces our blood pressure. Furthermore, any functions that were previously slowed down are started again (eg. digestion).

Question 24

EVALUATION: Fight-or-Flight

Answer 24

LIMITATION - ALTERNATIVE RESPONSE
P: Men and women respond differently to stressful situations
E: Taylor et al (2000) suggest that women show more ‘tend and befriend’ behaviours, which involves them protecting themselves and their young through nurturing behaviours and forming protective alliances with other women.
E: Women may have a different response because they are often the primary caregiver and feeing would put their offspring at risk.
L: Studies suggest that there may be physiological response to stress that inhibits flight - the release of the hormone oxytocin, which increases relaxation, reduces fearfulness and decreases the stress responses characteristic of the fight-or-flight response.

LIMITATION - NEGATIVE CONSEQUENCES
P: The stressors of modern day life rarely require the physical actively that fight-or-flight prepares the body for.
E: When the stress response is repeatedly activated, this can have an impact on humans wellbeing eg. increased blood pressure can lead to physical damage of blood vessels and eventually lead to heart disease.
E: In addition, although cortisol may assist the body fighting a viral infection or healing damaged tissue, too much cortisol suppresses the immune system, shitting down the process that fights infection.
L: Therefore, the limitation of fight-or-flight is that if too many stressful situations occur and the F/F response is triggered it may be damaging long-term. Maladaptive response in modern-day life.

LIMITATION - ALTERNATIVE RESPONSE 2
P: When faced with dangerous situations, our reaction is not limited to the fight-or-flight response, some psychologists suggest that humans engage in an initial ‘freeze’ response.
E: Gray (1998) argues that the first reaction to a threat is not to fight or flee but to avoid confrontation.
E: They argue that most animals typically first show the ‘freeze response’ where the animal is hypervigilant whilst they appraise the situation to decided the best course of action for that particular threat.
L: The adaptive advantages of this response for humans are that ‘freezing’ focuses attention and makes them look for new infarction in order to make the best response.

LIMITATION - RESEARCH IS ANDROCENTRIC
P: Early research into the fight-or-flight response was typically conducted on males (androcentrism), and consequently, researchers assumed that the findings could be generalised to females.
E: A reason why this research was carried out on males was because of the hormonal cycle of women which could impact the results of the study.
L: This highlights a beta bias within this area of psychology as psychologists assume that females responded in the same way as males until Taylor provided evidence of a tend and befriend response.

Question 25

L&L | What is localisation of function?

Answer 25

Localisation of function is the idea that certain functions (eg. language, memory etc) have certain locations or areas within the brain.
— This idea has been supported by recent neuroimaging studies but was also examined much earlier, typically using case studies.

Question 26

L&L | What is a study that has been used to examine localisation of function?

Answer 26

Case study on Phineas gage.
— In 1848 while working on a rail line, experienced a drastic accident during which a piece of iron went through his skull.
— He experienced a change in personality, such as loss of inhibition and anger.
— This change provided evidence to support the theory of localisation of brain function, as it was believed that the area the iron stake damaged was responsible for personality.

Question 27

L&L | What are the four key areas that you need to be aware of in localisation of function?

Answer 27

1. Motor
2. Somatosensory
3. Visual
4. Auditory areas

Two language centres:
1. Broca’s area
2. Wernicke’s area

Question 28

L&L | What is the motor area?

Answer 28

The motor area is located in the frontal lobe and is responsible for voluntary movements by sending signals to the muscles in the body.

Hitzig and Fritsch (1870) first discovered that different muscles are coordinated by different areas of the motor cortex by electrically stimulating the motor area in dogs.
— This resulted in muscular contractions in different areas of the body, depending on where the probe was inserted.

The regions of the motor area are arranged in logical order (eg. the region that controls the finger is located next to the region that controls the hand and arm and so on).

Question 29

L&L | What is the somatosensory area?

Answer 29

The somatosensory area is located in the parietal lobe and receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature etc.

Different parts of the somatosensory area receives messages from different locations of the body.
— Robert (1995) found that this area of the brain is highly adaptable
— Braille readers have larger areas in the somatosensory area for their fingertips, compared to normally sighted participants.

Question 30

L&L | What is the visual area?

Answer 30

At the back of the brain, in the occipital lobe, is the visual area, which receives and processes visual information.
— Information from the right-hand side visual field is processed in the left hemisphere
— Information from the left-hand side visual field is processed in the right hemisphere.

The visual area contains different parts that process different types of information, including colour, shape or movement.

Question 31

L&L | What is the auditory area?

Answer 31

The auditory area is located in the temporal lobe and is responsible for analysing and processing acoustic information.
— Information from the left ear goes primarily to the right hemisphere
— Information from the right ear goes primarily to the left hemisphere

The auditory area contains different parts, and the primary auditor area is involved in processing simple features of sound including volume, tempo and pitch.

Question 32

L&L - LC| Explain Broca’s area.

Answer 32

The Broca’s area is named after Paul Brice, who discovered this region while treating a patient who was referred to as Tan.
— He could understand spoken language but was unable to produce any coherent words, and could only say ‘Tan’.

After Tan’s death, Broca conducted a post-mortem examination on Tan’s brain and discovered that he has a lesion in the left frontal lobe.
— This led Broca to conclude that this area was responsible for speech production.
— People with damage to this area experience Broca’s aphasia, which results in slow and inarticulate speech.

Question 33

L&L - LC| Explain Wernicke’s area.

Answer 33

At a similar time to Broca, Carl Wernicke discovered another area of the brain that was involved in understanding language.
+ He found that patients with lesions to Wernicke’s area were still able to speak, but were unable to comprehend language.

Wernicke’s area is found in the left temporal lobe and is thought to be involved in language processing/comprehension.
— People with damage to this area struggle to comprehend language, often producing sentences that are fluent but meaningless (Wernicke’s aphasia).

Wernicke concluded that language involves a separate motor and sensory region. Motor region is located in Broca’s area, and the sensory region is located in Wernicke’s area.

Question 34

EVALUATION: Localisation of function

Answer 34

LIMITATION - EQUIPOTENTIALITY THEORY
P: One limitation is that not all psychologists area with the view that cognitive functions are localised in the brain.
E: Lashley (1930) introduced equipotentiality theory, which believes that basic motor and sensory functions are localised, but higher mental functions are not. Lashley argued that intact areas of the cortex could take over responsibility for specific cognitive functions following injuries to the area normally responsible for that function. According to this explanation, the effects of damage would be determined by the extent rather than localisation of the damage.
E: Further support for this theory has come from cases of human regaining some of their cognitive abilities following damage to specific areas of the brain, further suggesting that functions are not limited to one specific area of the brain.
L: Therefore, one limitation of the localisation theory is there is evidence to suggest that some functions can be carried out by different areas of the brain.

STRENGTH - EVIDENCE
P: A strength for the two language centres is that there is research support from aphasia patients.
E: Excessive aphasia (also known as Broca’s aphasia) is an impaired ability to produce language and in most cases caused by brain damage in Broca’s area. Receptive aphasia (also known as Wernicke’s aphasia) is an impaired ability to understand language, an inability to extract meaning from spoken or written word and is usually the result of damage in Wernicke’s area.
E: This therefore shows the importance of Broca’s area in the production of language and Wernicke’s area in the comprehension of language.
L: Therefore, one strength of the localisation of function is that it is supported by aphasia patients.

LIMITATION - INDIVIDUAL DIFFERENCES
P: A limitation of localisation of function is that there are individual differences.
E: Research from Bavelier et al (1997) found in a study of silent reading a variety of areas of the brain were activated across participants, including the right temporal lobe and left frontal, temporal and occipital lobes. In addition, Harsty et al (1997) found that women have proportionally larger Broca’s areas and Wernicke’s areas than men.
E: This is a problem for localisation of function as it suggests that where functions are located in the brain is not the same for everyone and can depend on the individual.
L: Therefore, one limitation of localisation of function is that individual differences mean it is not possible to generalise the same assumptions for everyone.

LIMITATION - BROCA
P: A limitation of Broca’s area is that language production may not be limited to that area alone.
E: Dronkers et al. (2007) re-examined the preserved brains of the two Broca’s patients using MRI imaging and found that other areas besides Broca’s area could also have contributed to the patients’ reduced speech abilities.
E: This is significant because although lesions to Broca’s areas alone can cause temporary speech disruption, they do not usually result in severe disruption of spoken language, suggesting that language and cognition are far more complicated and involve networks of brain regions rather than being localised to specific areas.
L: Therefore, a limitation of Broca’s area is that it alone does not appear to be responsible for language production.

Question 35

Lateralisation | What is Hemispheric Lateralisation?

Answer 35

Refers to the idea that two hales of the human brain are not exactly alike.

Question 36

Lateralisation | What is Split-Brain Research?

Answer 36

Split-brain research is the study of patients that had received surgery to isolate the two hemispheres from each other, enabling psychologists to study each hemisphere independently.
— This used to be a common treatment for epilepsy.

Question 37

Lateralisation | Explain Hemispheric Lateralisation in more depth.

Answer 37

Lateralisation is the idea that the two lhalbes of the brain are functionally different and that each hemisphere has functional specialisations (eg. the left is dominant for language and the right excels at visual-motor tasks.

The two hemispheres are context through nerve fibres called the corpus callosum, which facilities interhemisphetic communication - allowing the left and right hemisphere ‘talk to’ one another.

Question 38

Lateralisation | Explain Sperry and Gzzaniga (1967) split-brain research.

Answer 38

Split-brain patients are individuals who have undergone a surgical procedure where the corpus callosum, which connects the two hemispheres, is cut.
— This procedure, which separates the two hemispheres, was used as a treatment for severe epilepsy.

Sperry and Gazziniga (1967)
AIM: To examine the extent to which the two hemispheres are specialised for certain functions.

METHOD: An image / word is projected to the patient’s left visual field (which is processed in the right hemisphere) or the right visual field (processed by the left hemisphere).

When information is presented to one hemisphere in a split-brain patient, the information is not transferred to the other hemisphere (as the corpus callosum is cut).

Sperry and Gazziniga conducted many different experiments, including ‘describe what you see’ tasks, tactile tests and drawing tasks.

+ In the ‘describe what you see’ task a picture was presented to either the left or right visual field and the participant had to simply describe what they say
+ In the tactile test, an object was placed in the patient’s left or right hand and they had to either describe what they felt, or select a similar object from a series of alternate objects.

Question 39

Lateralisation | What were the findings and conclusion from Sperry and Gazziniga’s split-brain study?

Answer 39

> DESCRIBE WHAT YOU SEE
+ Right visual field (left hemisphere):
— The patient could describe what they saw, demonstrating the superiority of the left hemisphere when it comes to language production.
+ Left visual field (right hemisphere):
— The patient could not describe what was shown and often reported that there was nothing present.

> TACTILE TESTS
+ Right hand (left hemisphere):
— The patient could verbally describe what they felt. Or they could identify the test object presented in the right hand (left hemisphere), by selecting a similar appropriate object, from a series of alternate objects.
+ Left hand (right hemisphere):
— The patient could not describe what they felt a could only make wild guesses.
— However, the left hand could indemnify a test object present in the left hand (right hemisphere), by selecting a similar appropriate object, from a series of alternate objects.

CONCLUSION: The findings of Sperry and Gazziniga’s research highlights a number of key differences between the two hemispheres. The left hemisphere is dominant in terms of speech and language. The right hemisphere is dominant in terms of visual-motor tasks.

Question 40

EVALUATION: Split-Brain Research

Answer 40

STRENGTH - ENHANCES BRAIN EFFICIENCY
P: It assumed that the main advantage of brain lateralisation is that it increase neural processing capacity (the ability to perform multiple tasks simultaneously).
E: Rogers et al. (2004) found that in a domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously (finding food and being vigilant for predators). Using only one hemisphere to engage in a task leaves the other hemisphere free to engage in other functions.
E: This provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficient in cognitive tasks.
E: However, a limitation of this research is that it uses animals instead of humans, and fundamental differences between the two mean that this research has limited applicability.
L: Therefore, whilst a strength of lateralisation is that there is evidence that it enhances brain efficiency, it is important to consider the limitations of such research.

LATERALISATION + IMMUNE SYSTEM FUNCTIONING
P: It has been suggested that there is a relationship between hemispheric lateralisation and immune system functioning.
E: For example, those that are left-handed tend to have more superior right-hemispheric skills but are more likely to suffer higher rates of allergies and problems with the immune system.
E: Tonnessen et al. (1983) found a significant relationship between handedness and immune disorder whilst Morfit and Weekes (2001) found that left handers had a higher incidence of immune disorder in their immediate families than did right handers.
L: This therefore, suggests that the same genetic processes that lead to lateralisation may also affect the development of the immune system.

LATERALISATION CHANGES WITH AGE
P: Lateralisation of functioning seems to change throughout an individual’s lifetime with normal ageing.
E: 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.
E: Szaflarski et al. (2006) found that language became more lateralised to the left hemisphere with increasing age in children and adolescents, but after the age of 25, lateralisation decreased with each decade of life. It has been suggested that this may be to compensate for age-related declines in function in some way.
L: Therefore a limitation of lateralisation is that it does not apply equally to all age groups.

LIMITED GENERALISABILITY
P: The split-brain procedure is rarely carried out nowadays, meaning there is a limited number of individuals that can be used for research.
E: Andrews (20010 argues that many studies are presented with as few as three participants, or sometimes just the one.
E: Conclusions have therefore been drawn about the function of the brain from individuals who either have s confounding physical disorder (making the procedure necessary) or have had a less complete sectioning of the two hemispheres than was originally believed.
L: Therefore, a limitation of split-brain research is that it has limited generalisability to the wider population, limiting its usefulness.

Question 41

P+FR | What is plasticity?

Answer 41

Brain plasticity refers to the brain’s ability to change and adapt as a result of experience.

The ability to change plays an important role in brain development and behaviour.

Researchers used to believe that changes in the brain used to only take place in infancy and childhood.
— However, more recent research has demonstrated that the brain continues to create neural pathways and alter existing ones to adapt to new experiences as a result of learning.

Question 42

P+FR | What are some of the causes of plasticity?

Answer 42

— Life experiences
— Video games
— Meditation

Question 43

P+FR | What is functional recovery?

Answer 43

The brain also appears to show evidence of functional recovery: the transfer of functions from a damaged area of the brain after trauma to other undamaged areas.
— It can do this through a process termed neuronal unmasking where ‘dominant’ synapses (which have not received enough input to be active) open connections to compensate for a nearby damaged area of the brain.
— This allows new connections in the brain to be activated, thus recovering any damage occurring in specific regions.

Question 44

P+FR | EVIDENCE/ EVALUATION: Plasticity

Answer 44

STRENGTH - ANIMAL STUDIES
P: One strength for plasticity of the brain is that there is research support from animal studies.
E: Kempermann et al. (1998) investigated whether an enriched environment could alter the number of neurons in the brain of rats and found that those housed in complex environments had an increased number of neurons in the hippocampus in comparison to those housed in laboratory cages.
E: This supports plasticity of the brain as it shows how environmental factors can lead to changes in the development of neural pathways.
L: Therefore, one strength of plasticity is that research support is provided, although it is important to recognise the limitations of animal studies.

STRENGTH - HUMAN STUDIES
P: A strength of plasticity is that it is also supported by research into plasticity in humans.
E: Maguire et al. (2000) found that London taxi drivers have much larger posterior hippocampus compared to a control group and the size was positively correlated with the amount of time spent as a taxi driver.
E: This supports plasticity as it shows that complex memory training (taxi drivers must memories huge areas) can cause changes in certain areas of the brain.
L: Therefore, plasticity is also supported by research into plasticity in human, increasing its validity as a theory.

Question 45

P+FR | EVIDENCE/EVALUATION: Functional Recovery

Answer 45

STRENGTH - EDUCATIONAL ATTAINMENT
P: A strength of functional recovery is that research support has shown educational attainment can have an effect on recovery after a traumatic brain injury.
E: Schneider et al (2014) found that patients with the equivalent of a college education are seven times more likely to be disability-free a year after a moderate to traumatic brain injury compared to those who didn’t finish high school.
E: This is important as this suggests that those engaging in further education were in an environment that encouraged the development of neural pathways, aiding in their ability to recover from a brain injury.
L: Therefore, a strength of functional recovery is that data from humans supports it.

LIMITATION - AGE DIFFERENCES
P: A limitation of functional recovery that the ability of the brain to recover from trauma varies with age.
E: Studies have suggested that abilities thought to be fixed in childhood can still be modified in adults with intense training.
E: Despite these indicators of adult plasticity, Elbert et al (2001) conclude that the capacity for neural reorganisation is much greater in children than in adults, as demonstrated by the extended practice that adults require in order to produce changes.
L: Therefore, a limitation to functional recovery is that the older the individual is when trauma occurs, the more challenging it is to make and maintain changes.

Question 46

Studying the brain | What is functional Magnetic Resonance Imaging (fMRI)

Answer 46

Functional magnetic resonance imaging (fMRI) is a brain-scanning technique that measures blood blow in the brain when a person performs a task.

fMRI works on the premise that neurons in the brain that are the most active during a task, use the most energy,

Energy requires glucose and oxygen. Oxygen is carried in the bloodstream attached to haemoglobin (found in red blood cells) and is released for use by these active neurons, at which point the haemoglobin becomes deoxygenated.
— Deoxygenated haemoglobin has a different magnetic quality from oxygenated haemoglobin.
— An fMRI can detect different magnetic qualities and can be used to create a dynamic (moving) 3D map of the activities.
— fMRI images show activity approximately 1-4 seconds after they occur and are thought to be accurate within 1-2mm.
— An increase in blood flow is a response to the need for more oxygen in that area of the brain when it becomes active, suggesting an increase in neural activity.

Question 47

Studying the brain | EVALUATION: fMRI

Answer 47

STRENGTH - INVASIVE OR NON-INVASIVE
P: An advantage of fMRI is that it is non-invasive.
E: Unlike other techniques, for example, Positron Emission Tomography (PET), fMRI does not use radiation or involve inserting instruments directly into the brain and is therefore ritually risk-free.
E: Consequently, this should allow more patients / participants to undertake fMRI scans which could help psychologists to gather further data on the functioning human brain and therefore develop our understanding of localisation of function.

STRENGTH - SPATIAL RESOLUTION
P: fMRI scans have good spatial resolution.
E: Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect, and is an important feature of brain-scanning techniques.
E: Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accurate. fMRI scans have a spatial resolution of approximately 1-2mm which is significantly greater than other techniques (EEG, ERP etc.).
L: Consequently, psychologists can determine the activity of different brain regions with greater accuracy when using fMRI, in comparison to when using EEG /or ERP.

LIMITATION - TEMPORAL RESOLUTION
P: fMRI scans have poor temporal resolution.
E: Temporal resolution refers to the accuracy of the scanner in relation of time, or how quickly the scanner can detect changes in brain activity.
E: fMRI scans have a temporal resolution of 1-4 seconds which is worse than other techniques (EEG/ERP which have a temporal resolution of 1-10 milliseconds).
L: Consequently, psychologists are unable to predict with a high degree of accuracy, the onset of brain activity.

LIMITATION - CAUSATION
P: fMRI scans do not provide a direct measure of neural activity.
E: fMRI scans simply measure changes in blood flow and, therefore, it is impossible to infer causation (at a neural level).
E: While any change in blood flow may indicate activity within a certain brain area, psychologists are unable to conclude whether this brain region is associated with a particular function.
E: In addition, some psychologists argue that fMRI scans can only show localisation of function within a particular area of the brain, but are limited in showing the communication that takes place among the different areas of the brain, which might be critical to neural functioning.

Question 48

Studying the brain | What is an electroencephalogram (EEG)?

Answer 48

An electroephalogram (EEG) works on the premise that information is processed in the brain as electrical activity in the form of action potentials or nerve impulses, which are transmitter along neurons.

EEG scanners measure this electrical activity through electrodes attached to the scalp. Small electrical charges detected by the electrodes are graphed over a period of tine, indicating the level of activity in the brain.

There are four types of EEG pattern:
1) Alpha waves
2) Beta waves
3) Theta waves
4) Delta waves
— Each of these patterns has two basic properties that psychologists can examine:
1. Amplitude (the intensity or size of the activity)
2. Frequency (the speed of quantity of activity)

EEG patterns produce two distinctive states
> Synchronised pattern : where a recognised waveform (alpha, beta, delta and theta) can be detected.
> Desynchronised pattern : no pattern can be detected

Fast, desynchronised patterns are usually found when awake and synchronised patterns are typically found during sleep (alpha waves = light sleep, and delta/theta = deep sleep).
— EEG scanning was responsible for developing our understanding of REM (dream) sleep, which is associated with a fast, desynchronised activity, indicative of dreaming.

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.

Question 49

Studying the brain | What is Event-Related Potentials (ERP)?

Answer 49

Event-Related Potentials (ERPs) use similar equipment to EEGs, electrodes attached to the scalp. However, the key difference is that a stimulus is presented to a participant (for example, a picture/sound) and the researcher looks for activity related to that stimulus.

However, ERPs are difficulty to separate from all of the background EEG data, the stimulus is present many times (usually hundreds), and an average response is graphed.
— This procedure, which is called ‘averaging’ reduces any extraneous neural activity, which makes the specific response to the stimulus stand out.

The time or interval between the presentation f the stimulus and the response is referred to as latency. Waves (responses) that occur within 100 milliseconds following the presentation of a stimulus are referred to as sensory ERPs as they reflect a sensory response to the stimulus.
— ERPs that occur after 100 milliseconds are referred to as cognitive ERPs, as they demonstrate some information processing.

Question 50

Studying the brain | EVALUATION: EEG & ERPs

Answer 50

STRENGTH - NON-INVASIVE
P: An advantage of EEG and ERPs is that both techniques are non-invasive.
E: Unlike other scanning techniques, such as PET, EEG and ERPs do not use radiation or involve inserting instrument directly into the brain and are therefore virtually risk-free.
E: Furthermore, EEG and ERPs are much cheaper techniques in comparison with fMRI scanning and are therefore more readily available.
L: Consequently, this should allow more patients/participants to undertake EEG/ERPs, which could help psychologists to gather further data on the functioning human brain and therefore develop our understanding of different psychological phenomena, such as sleeping and different disorders like Alzheimer’s.

LIMITATION - SPATIAL RESOLUTION
P: One disadvantage of EEG/ERPs is that these techniques have poor spatial resolution.
E: Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect, and is an important feature of brain scanning techniques.
E: Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy. EEG/ERPs only detect the activity in superficial regions of the brain.
L: As a result, EEG and ERPs are unable to provide information on what is happening in the deeper regions of the brain (such as the hypothalamus), making this technique limited in comparison to the fMRI, which has a spatial resolution of 1-2mm.

STRENGTH - TEMPORAL RESOLUTION
P: An advantage for the EEG/ERP techniques is that they have good temporal resolution.
E: They take readings every millisecond mean the brain’s activity can be recorded in real-time as opposed to looking at a passive brain.
E: This leads to an accurate measurement of electrical activity when undertaking a specific task.
L: However, it could be argues that EEG/ERP, are uncomfortable for the participant, as electrodes are attached to the scalp. This could result in unrepresentative readings as the patient’s discomfort may affect the cognitive responses to situations. fMRI scans on the other hand are less invasive and would not cause the participants any discomfort, leading to potentially more accurate recordings.

> LIMITATION FOR EEG
P: Another issue with EEG is that electrical activity is often detected in several regions of the brain simultaneously.
L: Consequently, it can be difficult to pinpoint the extract area/region of activity, making it difficult for researchers to draw accurate conclusions.

> STRENGTH FOR ERP
P: ERPs enable the determination of how processing is affected by specific experimental manipulation.
L: This makes ERP use a more experimentally robust method as it can eliminate extraneous neural activity, something that other scanning techniques (including EEG) may struggle to do.

Question 51

Studying the brain | What are Post-Mortem Examinations?

Answer 51

A post-mortem examination can be used to allow researchers to study the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage.
— An example of this technique is the work of Broca, who examined the brain of a man who displayed speech problems when he was alive.
— It was subsequently discovered that he has a lesion in the area of the brain important for speech production.
— This later became known as Broca’s area.
— Similarly, Wernicke discovered a region int he left temporal lobe, which is important for language comprehension and processing - now known as Wernicke’s area.

This method of investigation has successfully contributed to the understanding of many disorders.
+ Iverson examined the brains of deceased schizophrenic patients and found that they all had a higher concentration of dopamine, especially in the limbic system, compared with the brains of people without schizophrenia, highlighting the importance of such investigations.

Furthermore, post-mortem studies allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with other techniques. They also enable researchers to examine deeper regions of the brain, such as the hypothalamus and hippocampus, something that is not easy with other methods of investigation.

Question 52

Studying the brain | EVALUATION: Post-Mortem Examination

Answer 52

LIMITATION - CAUSATION
P: One of the mian limitations of post-mortem examinations is the issue of causation.
E: The deficit a patient displays during their lifetime (eg. an inability to speak) may not be linked to the deficits found in the brain (eg. a damaged Broca’s area).
E: The deficits reported could have been the result of another illness, and therefore psychologists are unable to conclude that the deficit is caused by the damage found in the brain.
L: Additionally, another issue is that there are many extraneous factors that can affect the results/conclusions of post-mortem examinations. For example, people die at different stages of their life and for a variety of different reasons. Furthermore, any medication a person may have been taking, their age, and the length of time between death and the post-mortem examination, are all confounding factors that make the conclusion of such research questionable.

STRENGTH - DETAILED EXAMINATION
P: One strength of post-mortem is that they provide a detailed examination of the anatomical and neurochemical aspects of the brain that is not possible with other scanning techniques.
E: Post-mortem examinations can assess areas like the hippocampus and hypothalamus, which other techniques cannot, and therefore provide researchers with an insight into these deeper brain regions, which often provide a useful basis for for further research.
E: For example, Iverson found a higher concentration of dopamine in the limbic system of patients with schizophrenia, which has prompted a whole area of research looking into the neural correlates of this disorder.

LIMITATION? - INVASIVE?
P: While post-mortem examinations are ‘invasive’, this is not an issue because the person is dead.
E: However, there are ethical issues in relation to informed consent and whether or not a patient provides consent before his/her death.
E: Furthermore, many post-mortem examinations are carried out on patients with severe psychological deficits (eg. patient HM who suffered severe amnesia) who would be unable to provide fully informed consent, and yet these examinations were still conducted on their brains.
L: This raises severe ethical questions surrounding the nature of such investigations.

Question 53

BR | What are biological rhythms?

Answer 53

Biological rhythms are cyclical patterns within biological systems that have evolved in response to environmental influences (eg. day and night).

There are two key factors that govern biological rhythms:
1) endogenous pacemakers (internal factors)
2) exogenous zeitgebers (external factors)

Question 54

BR | What are circadian rhythms?

Answer 54

One of the biological rhythm is the 24-hour circadian rhythm (often known as the ‘body clock’), which is reset by levels of light.

The SLEEP-WAKE CYCLE is an example of a circadian rhythm; it dictates when humans and animals should be asleep and awake.
— Light provides the primary input to this system, acting as the external cue for sleeping or waking.

Light is first detected in the eye, which then sends messages concerning the level of brightness to the surachiasmatic nuclei (SCN).
+ The SCN then uses this information to coordinate the activity of the entire circadian rhythm.

Sleeping and wakefulness are not determined by the circadian rhythm alone, but also by homoeostasis.
+ When an individual has been awake for a long period of time, homoeostasis tells the body that there is a need for sleep because of energy consumption.
+ This homoeostasis drive for sleep increases throughout the day, reaching its maximum in the late evening when most people fall asleep.

BODY TEMPERATURE is another circadian rhythm.
— Human body temperature is at the lowest in the early hours of the morning (36 degrees celsius at 4:30am) and at its highest in the early evening (280*c at 6pm)
— Sleep typically occurs when the core temperature starts to drop and the body temperature starts to rise towards the end of a sleep cycle, promoting feelings of alertness first thing in the morning.

Question 55

BR | EVALUATION: Circadian Rhythms

Answer 55

STRENGTH - RESEARCH SUPPORT
P: Research has been conducted to investigate circadian rhythms and the effect of external cues like light on the system.
E: Siffre (1975) found that the absence of external cues significantly altered his circadian rhythm; when he returned from an underground stay with no clocks or light, he believed the date to be a month earlier than it was.
E: This suggests that his 24-hour sleep wake cycle was increased by the lack of external cues, making him believe one date was longer than it was, and leading to his thinking that fewer days had passed.
E: Siffre’s case study has been the subject of criticism. As the researcher and sole participant in his case study, there are severe issues with generalisability. However, further research by Aschoff & Weber provides additional support for Siffre’s findings. Aschoff & Weber studied participants living in a bunker. the bunker had no windows and only artificial light, which the participates erected free to turn on and off as they pleased.
E: They found that participants settled into a longer sleep-wale cycle between 25-27 hours.
L: These results, along with Siffre’s findings, suggest that humans use natural light (exogenous zeitgebers) to regulate a 24-hour circadian sleep-wake cycle, demonstrating the importance of light for this circadian rhythm.

LIMITATION - INDIVIDUAL DIFFERENCES
P: It is important to note the differences between individuals when it comes to circadian cycles.
E: Duffy et al. (2001) found that ‘morning people’ prefer to rise and go to bed early (about 6am and 10pm) whereas ‘evening people’ prefer to wake and go to bed later (about 10am and 1am).
L: This demonstrates that there may be innate individual differences in circadian rhythms, which suggests that researchers should focus on these differences during investigations.

TEMPERATURE IS MORE IMPORTANT THAN LIGHT?
P: It has been suggested that temperature may be more important than light in determining circadian rhythms.
E: Buhr et al. (2010) found that fluctuations in temperature set the timing of cells in the body and caused tissues and organs to become active or inactive.
E: Buhr claimed that information about light levels is transformed into neural messages that set the body’s temperature. Body temperature fluctuates on a 24-hour circadian rhythm, and even small changes in it can send a powerful signal to our body clocks.
L: This shows that circadian rhythms are controlled and affected by several different factors and suggest that a most holistic approach to research might be preferable.

Question 56

BR | What are endogenous pacemakers and exogenous zeitgebers?

Answer 56

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 regulate the internal biological clocks.

Question 57

BR | What are endogenous pacemakers?

Answer 57

Endogenous pacemakers are internal mechanisms that government rhythms, in particular, the circadian sleep-wake cycle.
— Although endogenous pacemakers are internal biological clocks, they can be altered and affected by the environment.
— Eg. 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.

The most important endogenous pacemaker is the suprachiasmatic nucleus, which is closely linked to the pineal gland, both are influential in maintaining the circadian sleep/wake cycle.

The suprachaismatic nucleus (SCN), which lies in the hypothalamus, is the main endogenous pacemaker (or master clock). It controls other biological rhythms as it links to other areas of the brain responsible for sleep and arousal. The SCN also receives information about light levels (an exogenous zeitgeber) from the optic nerve, which sets the circadian rhythm so that it is in synchronisation with the outside world (eg. day and night).

The SCN sends signals to the pineal gland, which leads to an increase in the production of melatonin at night, helping to induce sleep. The SCN and pineal glands work together as endogenous pacemakers; however, their activity is responsive to the external cue of light:

1. Low levels of light (retina)
2. Melanopsin carries signals to SCN
3. Axon pathway to pineal gland
4. Melatonin
5. Induced sleep

Question 58

BR | What are exogenous zeitgebers?

Answer 58

Exogenous zeitgebers influence biological rhythms - they can be described as environmental events that are responsible for resetting the biological clock of an organism.
— These can include social cues such as meal times and social activities, but the most important zeitgeber is light, which is responsible for resetting the body clock each day, keeping it on a 24-hour cycle.

The SCN contains receptors that are sensitive to light, and this external cue is used to synchronise the body’s internal organs and glands.
+ Melanopsin, which is a protein in the eye, is sensitive to light and carries the signals to the SCN to set the 24-hour daily body cycle.
+ In addition, social cues, such as meal times, can also act as zeitgebers and humans can compensate for the lack of natural light by using social cues instead.

Question 59

BR | EVALUATION: Endogenous Pacemakers & Exogenous Zeitgebers

Answer 59

STRENGTH - IMPORTANCE OF SCN + RESEARCH SUPPORT
P: There has been research to support the importance of SCN.
E: Morgan (1955) bred hamsters so that they had circadian rhythms of 20 hours, rather than 24 hours. SCN neurons from these abnormal hamsters were transplanted into the brains of normal hamsters, which subsequently displayed the same abnormal circadian rhythm of 20 hours, showing that the transplanted SCN had imposed its patterns onto the hamsters.
L: This research demonstrates the significance of the SCN and how endogenous pacemakers are important for biological circadian rhythms.
E: However, this research is flawed 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.
L: This makes research carried out on other animals unable to explain the role of endogenous pacemakers in the biological processes of humans.

STRENGTH - RESEARCH SUPPORT FOR MELANOPSIN
P: There is research support for the role of melanopsin.
E: Skene and Arendt (2007) claimed that the majority of blind people who still have some light perceptions have normal circadian rhythms, whereas those without any light perception show abnormal circadian rhythms.
L: This demonstrates the importance of exogenous zeitgebers as a biological mechanism and shows their impact on biological circadian rhythms.

STRENGTH - RESEARCH SUPPORT FOR EXOGENOUS ZEITGEBERS
P: There is further research support for the role of exogenous zeitgebers.
E: When Siffre returned from an underground stay with no clocks or light, he believed the date to be a month earlier than it was.
E: This suggests 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.
L: This highlights the impact of external factors on bodily rhythms.

LIMITATION - BIOLOGICALLY REDUCTIONIST
P: Despite all the research support for the role of endogenous pacemakers and exogenous zeitgebers, the argument could still be considered biologically reductionist.
E: For example, the behaviourist approach would suggest that bodily rhythms are influenced by other people and social norms i.e. sleep occurs when it is 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.
L: The research discussed here could be criticised for being reductionist as it only considers a singular biological mechanism and fails to consider the other widely divergent viewpoints.

Question 60

BR | What are infradian rhythms?

Answer 60

Infradian rhythms last longer than 24 hours and can be weekly, monthly and annually.

A monthly infradian rhythm is the female menstrual cycle, which is regulated by hormones that either promote ovulation or stimulate the uterus for fertilisation.
— Ovulation occurs roughly halfway through the cycle when oestrogen levels are at their highest and usually last 16-32 hours.
— After the ovulatory phase, progesterone levels increase in preparation for possible implantation of an embryo in the uterus.

It is also important to note that although the usual menstrual cycle is around 28 days, there is considerable variation, with some women experiencing a short cycle of 23 days and others experiencing longer cycles of up to 36 days.

Question 61

BR | EVALUATION: Infradian Rhythms

Answer 61

CRITICISM - GOVERNED BY EXOGENOUS ZEITGEBERS
P: Research suggests that the menstrual cycle is, to some extent, governed by exogenous zeitgebers (external factors).
E: Reinberg (1967) examined a woman who spent three months in a cave with only a small lamp to provide light.
E: Reinberg noted that her menstrual cycle shortened from the usual 28 days to 25.7 days.
L: This is result suggests that the lack of light (exogenous zeitgeber) in the cave affected her menstrual cycle, and therefore this demonstrates the effect of external factors on infradian rhythms.

CRITICISM - MORE RESEARCH EXOGENOUS ZEITGEBERS AFFECT INFRADIAN RHYTHMS
P: There is further evidence to suggest that exogenous zeitgebers can affect infradian rhythms.
E: Russel et al. (1980) found that female menstrual cycles became synchronised with other females odour exposure. In one study, sweat samples from one group of women were rubbed onto the upper lip of another group.
E: Despire the fact that the two groups were separate, their menstrual cycles synchronised. This suggests that the synchronisation of menstrual cycles can be affected by pheromones which have an effect on people nearby, rather than on the person producing them.
L: These findings indicate that external factors should be taken into account, as opposed to a reductionist approach that considers only endogenous influences.
— Evolutionary psychologists claim that the synchronised menstrual cycle provides an evolutionary advantage for groups of women, as the synchronisation of pregnancies means that childcare can be shared among multiple mothers who have children at the same time.

IMPORTANT REGULATORS OF BEHAVIOUR
P: There is research to suggest that infradian rhythms such as the menstrual cycle are also important regulators of behaviour.
E: Penton-Volk et al. found that women expressed a preference for feminised faces at the least fertile stage of their menstrual cycle, and for a more masculine face at their most fertile point.
L: These findings indicate that women’s sexual behaviour is motivated by the infradian rhythms, highlighting the importance of studying infradian rhythms in relation to human behaviour.

ROLE OF MELATONIN
P: There is evidence to support the role of melatonin in SAD (seasonal affective disorder).
E: Terman (1988) found that the rate of SAD is more common in Northen countries where the winter nights are longer. For example, Terman found that SAD affects roughly 10% of people living in New Hampshire (a northern part of the US) and only 2% of residents in South Florida.
L: These results suggest that SAD is, in part, affected by light (exogenous zeitgeber) which results in increased levels of melatonin.

Question 62

BR | What are ultradian rhythms?

Answer 62

Ultradian rhythms last fewer than 24 hours and can be found in the pattern of human sleep.
— This cycle alternates between REM (rapid eye movement) and NREM (non-rapid eye movement) sleep and consists of five stages.

The cycle starts at light sleep progressing to deep sleep and then REM sleep, where brain waves speed up and dreaming occurs. This repeats itself about every 90 minutes throughout the night.

A complete sleep cycle goes through the four stages of NREM sleep before entering REM and then repeating.
Research using EEG has highlighted distinct brain waves patterns during the different stages of sleep.

1. Stage 1 and 2 are ‘light sleep’ stages.
   — During these stages, brainwave patterns become slower and more rhythmic, starting with alpha waves progress to theta waves.
2. Stages 3 and 4 ‘deep sleep’ or slow-wave sleep stages (difficult to wake someone up).
   — This stage is associated with slower delta waves.
3. Finally, stage 5 is REM (dream) sleep.
   — The body is paralysed (to stop the person acting out their dream), and brain activity resembles that of an awake person.

On average, the entire sleep cycle repeats every 90 minutes, and a person can experience up to five full cycles in a night.

Question 63

BR | EVALUATION: Ultradian Rhythms

Answer 63

LIMITATION - INDIVIDUAL DIFFERENCES
P: The problem with studying sleep cycles is the differences observed in people, which makes investigating patterns difficult.
E: Tucker et al. (2007) found significant differences between participants in terms of the duration of each stage, particularly stage 3 and 4 (just before REM sleep).
E: This demonstrates that there may be innate individual differences in ultradian rhythms, which means that it is worth focusing on these differences during investigations into sleep cycles.
E: In addition, this study was carried out in a controlled lab setting, which meant that the differences in sleep patterns could not be attirubuted to situational factors, only to biological differences between participants.
L: While this study provides convincing support for the role of innate biological factors and ultradian rhythms, psychologists should examine other situational factors that may also play a role.

LIMITATION - LACK OF ECOLOGICAL VALIDITY
P: The way in which such research is conducted may tell us about ultradian rhythms in humans.
E: When investigating sleep patterns, participants must be subjected to a specific level of control and be attached to monitors that measure such rhythms.
E: This may be invasive for the participant, leading them to sleep in a way that does not represent their ordinary sleep cycle.
L: This makes investigating ultradian rhythms, such as the sleep cycle, extremely difficult as their lack of ecological validity could lead to false conclusions being drawn.

FLEXIBILITY IN ULTRADIAN RHYTHMS
P: There is research support that indicates the flexibility of ultradian rhythms.
E: Randy Gardener remained awake for 264 hours. While he experienced numerous problems such as blurred vision and disorganised speech, he coped rather well with the massive sleep loss. After this experience, Randy fell asleep for just 15 hours, and over several nights he recovered only 25% of his lost sleep.
E: Interestingly, he recovered 70% of Stage 4 sleep, 50% of his REM sleep and very little of the other stages.
L: 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.