biopsych

Question 1

Autonomic nervous system

Answer 1

nervous system responsible for automatic responses, involuntary movement such as sympathetic (fight or flight) or parasympathetic (rest or digest) responses
Also important role in homeostasis which maintains normal internal processes like body temperature, heart rate, blood pressure.
controlled by brain stem

Question 2

Broca’s area

Answer 2

Left hemisphere
Dedicated to speech production (motor component)
Damage leads to Broca’s aphasia - slow, inarticulate speech, short sentences, bad production but doesn’t affect comprehension
Near bottom of motor cortex, left frontal lobe

Question 3

Circadian rhythm

Answer 3

biological process cycle of 1 day (sleep-wake cycle)

Question 4

EEG A01

Answer 4

imaging technique to record electrical activity in brain

General Function only – not in relation to a task.

Electrodes are put on the scalp and detect electrical neuronal activity directly below where they are placed.

The scan recording represents the brainwave patterns that are generated from the area under each electrode.

Diagnostic tool as unusual patterns of activity may indicate neurological abnormalities such as epilepsy, tumours or disorders of sleep

Question 5

EEG A03

Answer 5

EEGs are cheaper compared to fMRI and so can be more widely used in research resulting in greater population validity.

Unlike fMRI, EEG technology has extremely high temporal resolution. Today’s EEG technology can accurately detect brain activity of a single millisecond (and even less in some cases).

EEGs have poor spatial resolution due to the generalised nature of the information received: The whole area under the electrode (thousands of neurons).

The EEG signal is not useful for pinpointing the exact source of neural activity, as activities originating in different but adjacent locations can become muddled.

Question 6

Endogenous pacemakers

Answer 6

Internal clocks that regulate biological rhythms (hormone levels)

Question 7

ERP A01

Answer 7

(event related potential)
imaging technique similar to EEC except baseline activity filtered so electrical activity in response to stimulus can be recorded

Function in relation to a task (not structure).

Similar to EEG’s but rather than general brain waves, they are designed to measure activity in response to a specific stimuli.

Using an averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to the presentation of a specific stimulus or performance of a specific task.

What remains are event-related potentials: types of brainwave that are triggered by particular events.

Question 8

ERP A03

Answer 8

ERPs are cheaper compared to fMRI and so can be more widely used in research resulting in greater population validity.

ERPs can pick up specific neural processes than just using raw EEG data and, although they do not have as good spatial resolution as fMRI, they are better than EEG alone.

As ERPs are derived from EEG measurements, they have excellent temporal resolution (see the activity on screen immediately) and this has led to their widespread use in the measurement of cognitive functions.

Critics have pointed to a lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings (reducing reliability).

Background noise and extraneous material must be completely eliminated, and this may not always be easy to achieve.

Question 9

Excitation

Answer 9

Signal sent to nerve to make it more likely to fire in synaptic transmission

Question 10

Exogenous zeitgebers

Answer 10

External cues that influence biological rhythms (sunlight levels)

Question 11

Role of adrenaline

Answer 11

General:

– prepare the body for action, fight or flight,

– increase blood supply/oxygen, to skeletal muscle for physical action

– increase oxygen to brain for rapid response planning

Direct:

– increase heart rate to increase blood flow to organs and muscles and increase the movement of adrenaline around the body

– constricts blood vessels, increasing rate of blood flow and raising blood pressure

– diverts blood away from the skin, kidneys and digestive system to re-divert energy for other stress response functions.

– increases respiration to increase oxygen intake and increased sweating to regulate temperature

Question 12

fMRI A01

Answer 12

(functional magnetic resonance imaging) - imaging technique which monitors blood flow in brain. Allows insight into which areas of brain used for particular activities

Measures brain activity while a person is performing a live task compared to a base line task.

Structure and function.

3D moving picture of the brain.

Large scanner uses a magnetic field to monitor blood oxygenation level (change in the energy released by haemoglobin).

When a brain area is more active it consumes more oxygen.

Question 13

fMRI A03

Answer 13

fMRI can only capture a clear image if the person stays perfectly still. This means that tasks being performed in the scanner have to be very simple and artificially constructed and so they often lack ecological validity as they do not fully represent real life tasks and emotions.

fMRI, unlike PET, does not use of radiation and so although it is uncomfortable it is risk-free and non-invasive making it a very ethical measuring tool for psychologists.

fMRI captures dynamic brain function/activity as opposed to post-mortem examinations which purely show physiology. This can be useful for showing cause and effect, such as what happens to a brain when a person feels anger, giving more internally valid results.

Interpretation of fMRI is affected by temporal resolution: there is a 5-second time-lag behind the image on screen and the initial firing of neuronal activity.

The results can be biased by the interpretation of the results and by the baseline task used, for example it may be leading in some way due to experimenter bias.

research is expensive leading to reduced sample sizes = low population validity

very good spatial resolution, depicting detail by the millimetre, and providing a clear picture of how brain activity is localised. However, fMRI can only measure blood flow in the brain, it cannot show the activity of individual neurons and so it can be difficult to tell exactly what kind of brain activity is represented on screen

Question 14

Hormones

Answer 14

chemical messengers that travel in blood stream to regulate certain processes in body

Question 15

infradian rhythms

Answer 15

biological rhythms that last longer than a day (menstrual cycle)

Question 16

inhibition

Answer 16

signal sent to next nerve to make it less likely to fire

Question 17

lateralisation of function A01

Answer 17

Different hemispheres in brain have different functions -
Left hemisphere typically language (Broca + Wernicke), logical and analytical thought, focus on detail, systems and rules
Right hemisphere typically face recognition, spatial tasks, empathy, emotion and intuition

Question 18

localisation of function A01

Answer 18

functions in brain specific to certain areas - Broca’s area, Wernicke’s area. motor cortex, somatosensory cortex, temporal lobe, occipital lobe

Question 19

motor neuron

Answer 19

neuron transfers info from CNS to activate effectors (muscles, glands, organs)
Nodes, myelin sheath

Question 20

peripheral nervous system

Answer 20

nervous system that isn’t CNS

Question 21

plasticity

Answer 21

Ability of brain to adapt to situations and change its structure - even to potentially regain lost function

Question 22

relay neurons

Answer 22

neuron found in CNS which allows communication between sensory and motor neurons - aid decision making
very basic dendrite, cell body, axon, pre-synaptic terminal

Question 23

sensory neurons

Answer 23

neurons that transmit sensory information from the peripheral nervous system to relay neurons in CNS
cell body not at end with dendrite, further along

Question 24

somatic nervous system

Answer 24

nervous system in control of conscious, voluntary movements of the periphery (picking something up)
transmits info received by senses through receptors to CNS and transmits messages from CNS to effectors so has sensory and motor pathways
commanded by brain’s sensory and motor cortex

Question 25

suprachiasmatic nucleus

Answer 25

two small paired nuclei in brain responsible for controlling many circadian rhythms in body (regulate sleep-wake cycle)

Question 26

ultradian rhythms

Answer 26

biological rhythms that occur multiple times in one day (sleep cycle which occurs every 90 minutes)

Question 27

Wernicke’s area

Answer 27

Left hemisphere
Dedicated to language processing/comprehension
Damage leads to still speaking fluent sentences but meaningless, struggle to comprehend language
Where left temporal and parietal lobe meet

Question 28

Neurotransmitters

Answer 28

• Information about anything and everything is communicated via neurotransmitters.
• These are biochemical’s (chemicals produced by our body) which the brain recognises as prompts or signals for specific thoughts, feelings, actions and responses.
• Everything we think or do can be reduced down to a specific combination of neurotransmitters sent around our brain.
• Their exact numbers are still unknown but more than 100 chemical messengers have been identified
• It has also been possible to identify that certain imbalances of neurotransmitters are responsible for a range of problems, such as the symptoms of mental health conditions.
• For example, serotonin, which regulates mood, has been implicated in OCD

Question 29

Synaptic transmission process

Answer 29

· Electrical impulses called action potential carry vesicles containing a specific neurotransmitter, for example serotonin, through the transmitter neuron to the presynaptic axon terminal.

· Fire: This electrical impulse then triggers the release of the neurotransmitter into the synapse (the gap between the transmitter and receptor neuron).

· Bind: The neurotransmitter then crosses the synapse and binds to receptor sites on the postsynaptic membrane of the dendrite of the receptor neuron.

· This stimulation of the postsynaptic receptor sites by the neurotransmitter result in either excitation or inhibition of the postsynaptic membrane.

· If the neurotransmitter is excitatory then the post synaptic neuron receiving it is more likely to fire an impulse.

· If the neurotransmitter is inhibitory then the post synaptic neuron receiving it is less likely to fire an impulse.

· Summation: The excitatory and inhibitory influences are added together. If the total effect on the post synaptic neuron is inhibitory and threshold is not reached, the neuron will not ‘fire’ and if the total effect is excitatory, the neuron will reach threshold and create an action potential in order to fire

Question 30

Post-mortem A01

Answer 30

Brain is examined after death to try and correlate structural abnormalities/damage to behaviour the person displayed while alive.

Likely to be those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime.

Structure not function

Question 31

PNS

Answer 31

peripheral nervous system - split into somatic and autonomic nervous system
nervous system everywhere except CNS

Question 32

Endocrine system

Answer 32

Hormones secreted into blood stream by glands to target organs.
Command centre is hypothalamus which communicates with pituitary gland
works closely with nervous system as neural messages tell gland when to release hormones
some released as stress response (fight or flight) but some automatic to maintain body function (oestrogen to control menstrual cycle)

Question 33

Pituitary gland

Answer 33

Hypothalamus
growth hormone/hormones that stimulate all other glands e.g. LH & FSH to ovaries

Question 34

Thyroid gland

Answer 34

Base of neck
thyroid hormone (metabolism and digestion)

Question 35

Adrenal gland

Answer 35

Top of kidneys
adrenaline (medulla) and cortisol (cortex) – prepares body to respond to stress

Question 36

Pancreas

Answer 36

Insulin digests sugar and supplies body with energy

Question 37

Testes

Answer 37

testosterone – leads to feelings of dominance, aggression and competitiveness, regulates reproductive cycle

Question 38

Ovaries

Answer 38

progesterone / oestrogen / testosterone – regulates reproductive cycle, oestrogen leads to emotional regulation, feelings of nurturing and can affect memory and cognition

Question 39

What is fight or flight

Answer 39

The fight or flight response involves the sympathetic branch of the ANS and the adrenal medulla. Body’s instinctive way of responding to acute (immediate and severe) stress and so is instinctive and happens without conscious thought.

Originally it was designed to keep us alive in the face of sabre-toothed tigers and lions but now in our modern world we perceive other things as acutely stressful, such as exams and public speaking, but also still serious things like getting mugged or run over

Question 40

Outline fight or flight response

Answer 40

Step 1: A threat (an attack, harmful event or threat to survival).

Step 2: The brain processes the sensory input and the hypothalamus prepares the body for action.

Step 3: The hypothalamus sends the neurotrasmitter noradrenaline down the sympathetic branch of the autonomic nervous system until it reaches the adrenal gland.

Step 4: The adrenal medulla (middle part of the adrenal gland) releases the hormone adrenaline into the blood stream where is travels to relevant organs.

Step 5: Action occurs, typically running away or fighting

Step 6: The threat has passed and so the parasympathetic branch of the ANS is turned on to return our body to a normal resting state/ normal level of functioning.

Question 41

Evaluate fight or flight

Answer 41

· When faced with a dangerous situation our reaction is not limited to the fight or flight response; some psychologists suggest that humans engage in an initial ‘freeze’ response; that the first response to danger is to avoid confrontation altogether, which is demonstrated by a freeze response. During the freeze response animals and humans are hyper-vigilant, while they appraise the situation to decide the best course of action for that particular threat.

· Research into the fight or flight response was originally conducted on males (androcentrism) and consequently, researchers assumed that the findings could be generalised to females. This highlights a beta bias within this area of psychology as psychologists assumed that females responded in the same way as males, actually this is not true (see below point).

· Recent research suggests that females do not always carry out a ‘fight or flight’ response and instead adopt a ‘tend and befriend’ response in stressful/dangerous situations. Women are more likely to protect their
offspring (tend) and form alliances with other women (befriend), rather than fight an adversary or flee. Furthermore, the fight or flight response may be counterintuitive for women, as running (flight) might be seen as a sign of weakness and put their offspring at risk of danger.

· While the fight or flight response may have been a useful survival mechanism for our ancestors, who faced genuinely life-threatening situations (e.g. from predators), modern day life rarely requires such an intense biological response. The stressors of modern day life can repeatedly activate the fight or flight response, which can have a negative consequence on our health. For example, humans who face a lot of stress and continually activate the sympathetic nervous system, continually increase their blood pressure, which can cause damage to their blood vessels and heart disease. This suggests that the fight or flight response is a maladaptive response in modern-day life (an example of ‘miss-match’ in evolutionary psychology).

Question 42

Motor cortex

Answer 42

Both hemispheres - cross wired
Voluntary movement - more movement, more neurons dedicated to it
Damage leads to paralysis or difficulty moving desired area of body
Arch of nerve fibres found at rear of both frontal lobes

Question 43

Somatosensory cortex

Answer 43

Both hemispheres - cross wired
Processes sensory info, more we can feel an area, the more neurons dedicated to it
Damage leads to loss of feeling to area of body neurons correspond to
Arch of nerve fibres at front of parietal lobes, next to motor area

Question 44

Visual area

Answer 44

Both hemispheres - cross wired visual fields
Receives and processes visual info, different parts process different info eg. colour, shape or movement
Occipital lobe at back of brain

Question 45

Auditory area

Answer 45

Both hemispheres - cross wired ears
Analyses and processes auditory info, different parts: primary auditory area processes simple features of sound eg. volume, tempo and pitch
Damage leads to hearing loss (if Wernicke’s area then Wernicke’s Aphasia)
Temporal lobe (under each ear)

Question 46

How Broca’s area discovered

Answer 46

The Broca’s area is named after Paul Broca, who discovered this region while treating a patient. The patient (Leborgne) could understand spoken language but was unable to produce any coherent words, and could only say ‘Tan’. After his death, Broca conducted a post-mortem examination on his brain and discovered that he had a lesion in the left frontal lobe. This led Broca to conclude that this area was responsible for speech production.

Question 47

How was Wernicke’s area discovered

Answer 47

Carl Wernicke discovered another area of the brain in the left temporal lobe that was involved in understanding language. Wernicke found that patients with lesions to Wernicke’s area were still able to speak, but were unable to comprehend language. Therefore Wernicke’s area thought to be involved in language processing/comprehension

Question 48

Localisation A03

Answer 48

Research evidence – Phineas Gage (plus evaluation):
Whilst working on the railroad in 1848, Phineas Gage caused an explosive which sent a metre-length metal pole through Gage’s left cheek, passing behind his left eye, and exiting his skull from the top of his head taking most of his left frontal lobe with it. Incredibly, Gage survived but the damage to his brain had left a mark on his personality – by all accounts he had turned from someone who was calm and reserved to someone who was quick-tempered, rude and ‘no longer Gage’.
This supports localisation as it suggests that the frontal lobe may be responsible for regulating mood and influence out personality. However, an issue with this research is that it’s a case study so lacks population validity. This means the data gained is specifically relevant to Phineas Gage and the unique trauma and secondary effects (such as widespread infection) of his accident. It’s unlikely that someone else with frontal lobe damage will present in the same way as the extent of the injury may not be the same. Therefore, the Phineas Gage case study was only useful to trigger more scientific and generalisable research in the future.

Research evidence – Broca (plus evaluation):
Research to support localisation is contradictory and of varied quality. Broca supported his theory by using correlational evidence from a post mortem of a patient; he linked a damaged brain area in the lower portion of the left frontal lobe to unique symptoms shown during the patient’s life; the patient could not speak apart from one word but could understand what was being said to him. This supported the idea that this region is specialized in language production, however this is not very internally valid as post-mortems cannot show live behaviour, other potential causes cannot be ruled out. More recent research has provided contradictory evidence. In 2007 another psychologist conducted an MRI scan on Broca’s same patents preserved brain, to try to confirm Broca’s findings. Although the same lesion was found in Broca’s area, they also found evidence to suggest other areas may have contributed to the failure in speech production. The use of the MRI is more valid than a post-mortem and can pick up areas a human may miss. These results suggest that language production is not as localised to only Broca’s are as first thought.

Alternative idea – plasticity:
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 that higher mental functions are not. He claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following brain injury. This therefore undermines localisation theory as it states that brain areas can carry out a wide variety of functions.

Debates:
Critics argue that theories of localisation are reductionist 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.

Some psychologists argue that the idea of localisation fails to consider individual differences. Herasty found that women have proportionally larger Broca’s and Wernicke’s areas than men, which can perhaps explain the greater ease of language use amongst women. This, however, suggests a level of beta bias in the theory: the differences between men and woman are ignored, and variations in the pattern of activation and the size of areas observed during various language activities are not considered.

Question 49

Outline split brain research

Answer 49

Split-brain research has shown how each hemisphere of the brain is able to function quite independently. It can also show what each hemisphere is responsible for.

Split-brain patients are individuals who have had their corpus callosum cut so that the two hemispheres are no longer connected and cannot communicate with each other. This procedure was mainly used in the 1950’s to treat epileptic patients. As a result of this procedure, the two hemispheres of the brain are not able to communicate with each other.

• A psychologist named Sperry saw 11 epileptic patients being treated at the university hospital where he worked, and realised they presented a unique opportunity to study the functioning of the hemispheres of the brain when they were independent from each other and to examine the extent to which the two hemispheres are specialised for certain functions.
• Sperry conducted many experimental tasks where only one hemisphere at a time was given information or asked a question.
• Split visual field tasks involved showing the pp a word or image to only one visual field and asking them to name or draw the object. Objects presented to the left visual field go only to the right hemisphere and so cannot be named (in fact the PP will report having seen nothing as the vocal left hemisphere has indeed seen nothing) but can be drawn with the left hand. Objects presented to the right visual field can be named as they go to the speaking left hemisphere, they can also be drawn with the right hand but the right hand is not as good at drawing as the left hand is (even if the person used to be right handed.
• When asked to solve a wooden block puzzle the left hand and right hemisphere is superior.
• The findings of Sperry’s research highlight a number of key differences between the two hemispheres. Firstly, the left hemisphere is dominant in terms of speech and language. Secondly, the right hemisphere is dominant in terms of visual-motor tasks.

Question 50

Evaluate split-brain research

Answer 50

The experiments allowed for high levels of control. They were able to isolate each hemisphere and control situational variables through the artificial tasks to establish cause and effect

The data was artificially produced and the tasks used were very simplistic; the findings of the study would be unlikely to be found in a real-life situation because a person with a severed corpus callosum would be able to compensate for such a loss by using both visual fields.

Research relates to small sample sizes which means it is not very representative, however Sperry did not have control over this - there were not very many split-brain patients available to study. The small sample also enabled Sperry to gain more in-depth data.

Question 51

Evaluate lateralisation

Answer 51

Split-brain research

Research Evidence:
Rogers found that in a domestic chicken brain lateralisation was 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. This provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in cognitive tasks. It was concluded that the main advantage of brain lateralisation is that it increases neural processing capacity (the ability to perform multiple tasks simultaneously).
However, findings from such animal studies cannot be fully extrapolated as humans have a far larger cortex than any other animal which is capable of far greater cognitive processes that cannot be observed and tested in chickens

Overemphasises and oversimplifies the functional distinction between the left and the right hemispheres. Although ‘verbal’ and ‘non-verbal’ labels can occasionally be usefully applied to summarise the differences between the hemispheres, modern neuroscientists would state that the distinction is less clear cut. In the normal brain the two hemispheres are in constant communication when performing all tasks and many behaviours typical of one hemisphere can be carried out by the other when the situation requires or if the usual area gets damaged – plasticity

Question 52

Brain plasticity A01

Answer 52

Brain plasticity refers to the brain’s ability to change and adapt in reaction to the environment and through experience. An example of this is when learning a new skill develops neuronal connections in the related area of the brain.
During childhood, the brain experiences a rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 at age 2-3 years. This equates to about twice as many as there are in the adult brain. As we age, rarely used connections are deleted and frequently used connections are strengthened – a process known as synaptic pruning.

It was originally thought that such changes were restricted to the developing brain within childhood, and the adult brain, having moved beyond a critical period, would remain fixed and static in terms of function and structure. However, more recent research suggests that at any time in life existing neural connections can change, or new neural connections can be formed, as a result of learning and experience (plasticity)

Question 53

brain plasticity A03

Answer 53

Research evidence – Maquire:
Maquire et al. studied the brains of London taxi drivers and found significantly more volume of grey matter in the back part of the hippocampus than in a matched control group.
This part of the brain is associated with the development of spatial and navigational skills in humans and other animals.
As part of their training, London cabbies must take a complex test called ‘The Knowledge’, which assesses their recall of the city streets and possible routes.
It appears that as a result of this ‘learning experience’ the structure of the taxi drivers brains were altered. It is also noteworthy that the longer they had been in the job, the more pronounced was the structural difference was.
These findings have good internal validity since empirical and unbiased brain scanning methods were used and they included comparison to a control group, where potentially confounding participant variables (prior education and employment) were controlled for using a matched pairs design. This suggests that the study can be used as strong evidence of neuroplasticity.

Research evidence – similar findings:
Medical students who were scanned three months before and after their final exams showed learning-induced changes in the posterior hippocampus and the parietal cortex.
Bilingual people have a larger parietal cortex compared to matched monolingual controls.
Video game training results in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance- skills that were important in playing the game.

AO3 Optional Extension - The effects of mediation:
Davidson et al. (2004) compared eight practitioners of Tibetan meditation with 10 student volunteers with no previous meditation experience. Both groups fitted with electrical sensors and asked to meditate for short periods.
Electrodes picked up much greater activation of gamma waves (important because they coordinate neuron activity) in the monks.
The students showed only a slight increase in gamma wave activity while meditating.
This demonstrates that meditation changes the working of the brain in the short term and may also produce permanent changes as the monks had far more gamma wave activity than the control group even before they started meditating.

Question 54

Functional recovery A01

Answer 54

The functional recovery that may occur in the brain after trauma is another example of neural plasticity and follows physical injury to the brain, or other forms of trauma that damage the brain such as the experience of a stroke.

• Unaffected areas of the brain are often able to adapt and compensate for those areas that are damaged, this is called ‘neural reorganisation’.
• There can also be a growth of new neurons and/or connections to compensate for damaged areas, this is called ‘neural regeneration’ or axonal sprouting!
• The final process that can occur is ‘neuronal unmasking’ where previously dormant 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.
• Plasticity allows the brain to cope with the main damage and also with some of the ‘indirect’ effects of brain damage e.g. swelling and haemorrhage (bleeding) following road accident.

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 require rehabilitative therapy to further their recovery.

When the person is young, and the brain is still maturing, recovery from trauma is more likely, but can also happen for older people.

Question 55

Functional recovery A03

Answer 55

Research evidence – case study and evaluation (can also be used as contradictory evidence for localisation/lateralisation)
Jodi Miller was having severe epileptic seizures almost constantly. To cure these they surgically removed her entire right hemisphere.
As quickly as upon waking from the operation, her left hemisphere had already taken over the function of moving her left leg (previously undertaken by her now missing right hemisphere).
Following physiotherapy Jodi is now almost fully functional on her left side due to neural reorganisation – her left hemisphere has learnt to do what the right hemisphere used to.
However, due to ethical restrictions psychologists studying functional recovery like this must rely on these rare case studies which involve unique damage and may not be fully generalisable to functional recovery in the average person.

Research evidence – Experiment by Biernaskie:
Psychologists (Biernaskie et al) have demonstrated that improvements to movement following brain injuries like strokes may be because the motor cortex of the undamaged hemisphere picks up the job of the damaged hemisphere.
Firstly, they damaged the motor cortex of rats in the right hemisphere, specifically to hinder left forelimb function. They then gave the rats intensive rehabilitation for 4 weeks until they were again able to use this limb.
Finally, they injected the undamaged motor cortex in the other, left, hemisphere to prevent it from working.
The result was that the rat could no longer use their originally damaged left limb.
This shows that during the rehabilitation process the left hemisphere had picked up the job of moving the left limb which the right hemisphere motor cortex was no longer able to do.
This experiment has greater internal validity than the case study because the psychologists were able to control the damage thanks to fewer ethical restrictions when testing animals.
However, as a result it also has lower external validity than the case study as findings from such animal studies cannot be fully extrapolated as humans have a far larger cortex than any other animal which is capable of far greater cognitive processes that cannot be observed and tested in rats.

Practical application:
Understanding the processes involved in plasticity has contributed to the field of neuro-rehabilitation.
Following illness or injury to the brain, spontaneous recovery tends to slow down after a number of weeks so forms of physical therapy may be required to maintain improvements in functioning.
Techniques may include movement therapy and electrical stimulation of the brain to counter the deficits in motor and/or cognitive functioning that may be experienced following a stroke, for instance.
This shows that, although the brain may have the capacity to ‘fix itself’ to a point, this process requires further intervention if it is to be completely successful

Optional Extension: AO3 Negative Functional Recovery /plasticity:
The brain’s ability to rewire itself can sometimes have negative consequences.
Prolonged drug use, for instance, has been shown to rewire the brain in that neurons learn to compensate from increased levels of a neurotransmitter by growing more receptors, this is one reason why people become dependent on drugs and also why prescriptions for anti-psychotics have to be continually adjusted.
Also, 60-80% of amputees have been known to develop phantom limb syndrome – the continued experience of sensations in the missing limb as if it were still there. These sensations are usually unpleasant, painful and are thought to be due to neural reorganisation in the somatosensory cortex that occurs as a result of limb loss.

Question 56

Sleep cycle A01

Answer 56

4 stages last 90 minutes all together, several cycles every night (4-5):
- stages 1-3 Non-REM (rapid eye movement), each stage progressively deeper and brainwaves slower and harder to wake, stage 3 deep sleep
- stage 4 REM (dream) sleep, brain activity resembles that of awake person
- each time cycle happens, stage 3 gets shorter and REM gets longer
- sleep spindles are sudden bursts of brain activity in stage 2. Represent times where brain inhibits mental processing in order to keep person in tranquil state so can progress to deep sleep

Question 57

Ultradian rhythms A03

Answer 57

AO3: Research into ultradian rhythms: Dement and Kleitman
9 pps were studied under controlled laboratory conditions, controlling for extraneous variable like caffeine and alcohol consumption.
They went to bed in a quiet, dark room and an electroencephalograph (EEG) was used to amplify and record the signals of electrodes which were attached to the participants face (eyes) and scalp.
All the participants showed periods of REM every night during sleep. The REM EEG was characterised by a relatively fast pattern.
In between REM periods the EEG patterns were either slow activity or spindles, both characteristic of deeper sleep.
REM never occurred at the beginning of the sleep cycle.
REM periods which were not terminated by an awakening varied between 3 minutes and 50 minutes with a mean of about 20 minutes, and they tended to increase in length as the night progressed.
The REM periods occurred at regular intervals during the night, though each participant has their own pattern: the mean period between each REM phase for the whole group was 92 minutes, with individual norms varying between 70 minutes and 104 minutes.
This supports the sleep-cycle as an ultradian rhythm with multiple cycles occurring each night.
This study uses objective measurements and took place in an environment where extraneous situational variables were eliminated resulting in high internal validity.
Although the findings are based on a very small sample size replications have found similar findings supporting the theory that there are multiple sleep cycles throughout a single night’s sleep.

AO3: BRAC
Following research has suggested that a 90-minute ultradian rhythm continues throughout the daytime also. Rather than moving through stages of sleep, we pass through stages of alertness into tiredness each 90 minutes with a lack of concentration, hunger and fatigue needed at the end of each 90 mins. He called this the ‘Basic Rest Activity Cycle’ or ‘BRAC’ for short.
Ericsson et al provide research for a BRAC. They studied a group of elite violinists and found that they limited their practise sessions to no more than 90 minutes at a time, with practise sessions distributed through the day in 90-minute segments. The violinists would even nap to recover from these practise sessions.
Ericsson went on to discover the same pattern across other musicians, athletes, chess players and writers.

AO3: General evaluation
A general evaluation point is that sleep cycles do vary with individual differences like age. Older people find it takes them longer to fall asleep and spend less time in REM sleep and much less time in deep slow wave sleep than younger people

Question 58

Sleep/wake cycle A01

Answer 58

Endogenous pacemakers affecting the sleep/wake cycle:
The SUPRACHIASMATIC NUCLEUS (SCN) is a tiny cluster of neurons is located in the hypothalamus and is connected to the part of the brain where the optic nerves cross over and so it receives information about the amount of external light in the environment. When light levels fall the SCN sends signals to the pineal gland which induces the production of the sleep hormone melatonin. This inhibits the brain mechanisms that promote wakefulness causing sleep to occur.
Even without light, the SCN is still able to control a rise and fall of melatonin internally, suggesting that is the site of the main internal biological clock. Humans have a biological/ internally driven 25 hour endogenous biological clock which is kept to 24 hours by the external zeitgeber of light.
Once the SCN detects rising light levels it tells the pineal gland to stop producing melatonin and our brain gradual starts becoming disinhibited. The adrenal glands also secrete cortisol each morning just before dawn. Cortisol therefore must be controlled by a biological clock mechanism. One psychologist removed tissue from the gland and grew an adrenal gland in a lab: It continued to secrete cortisol at the same time each day. This means that the tissue in our adrenal glands must possess an endogenous clock (internal body clock).

Exogenous zeitgebers affecting the sleep/wake cycle:
Light influences the production of melatonin from the pineal gland which influences people’s sleep/wake cycle. For this reason light is considered to be the dominant exogenous zeitgeber in the sleep-wake cycle because the SCN receives light information directly from the optic nerve. This is likely due to evolutionary factors as exogenous zietgebers alert individuals to changes in the likelihood of possible rewards or threats in the environment. For example, humans are more likely to find food and shelter in the daytime and less likely to detect predators in the night, meaning wakefulness tends to be most beneficial during the day and sleep is best saved for the night: This means we have evolved so that changes in light and darkness influence the body to rise during the day and become fatigued at night.

External cues and social stimuli as exogenous zeitgebers:
Different cultures that may have the same light hours in a day can still have different sleep-wake patterns and when external light cues can be disregarded other factors can take over, e.g. in the arctic circle people still sleep for around 7 hours a day, even during the summer when the sun never sets. This is because there are other external influences on the sleep-wake cycle such as clocks, temperature, exercise, social interactions, drug manipulation, meal times or work practises.
We can also look at babies as an example of social cues. When they are born their sleep patterns are random but by 6 weeks most are entrained by their parents to fit their social schedule of meal times and bedtimes, despite the fact that biological circadian rhythms don’t begin until much later at 16 weeks.

Disruption to the sleep/wake cycle:
Since the internal clock (SCN) sets itself using exogenous zeitgebers, the loss or disruption of an individual’s usual zeitgebers can be very disorienting. When an individual experiences significant changes in zeitgebers, such as being irregularly scheduled for the night shift, those changes can have a variety of negative effects. This is called ‘de-synchronisation’; another example of this is jetlag. Such zeitgeber disruptions can lead to decreased cognitive performance, negative mood, and in some cases, episodes of mental illness. Apparently the best medicine for jetlag is to adjust quickly to the new exogenous zeitgebers by working with the new countries meal and sleep times rather than following your urges set by the previous time zone.

Question 59

Circadian rhythms A03

Answer 59

Research 1 into circadian rhythms – Morgan’s hamsters
Morgan found that if the SCN of a hamster is removed, then their circadian rhythms will disappear completely.
They were then able to re-establish the rhythms by transplanting SCN cells from foetal hamsters.
Similarly, when the Morgan gave the hamster a transplanted SCN from another animal (e.g. from a mutant strain of hamster with a shorter cycle of 20 hours), it will adopt the same activity patterns as the donor animal. This suggests that the sleep wake cycle is based entirely on internal zeitgebers as without them the cycle disappeared.
However, animals do not have as many social and cultural influences on their rhythms as humans and are more dependent on biological processes. They are still vulnerable to environmental pressures, such as sleeping during the main heat of their dessert habitat, and may not have been able to amend their cycles as much as humans have. T
his means this animal data cannot be fully extrapolated to what controls human cycles.

AO3: Research 2 into circadian rhythms – Michel Siffre
Siffre lived for 2 months in a dark cave alone with no exogenous zeitgebers to see what his sleep wake cycle would be like. He did not take a clock with him and had no daylight to mark the passing of time.
He called the surface regularly to keep a record of when he slept and woke.
Despite not having an accurate perception of the date (behind by 25 days), his body had kept its own rhythm to a cycle.
Siffre had discovered the human body’s internal clock was controlled primarily by endogenous pacemakers. Independent of the external zeitgeber of natural light Siffre’s sleep wake cycle had remained constant at around 25 hours, rather than the usual twenty-four hours.
The role of the exogenous zeitgebers therefore appears to be to retrain the clock every day to suit our lifestyles and match the rotation of the earth.
However, this research was faulty because it failed to shield Siffre from artificial light; at the time psychologists were not aware of the phase-delaying effects of electric lights. Electric light in the evening may have delayed his circadian phase.
More recent research not involving electric light has shown that the range for normal, healthy adults of all ages is quite narrow; 24 hours and 11 minutes. The “clock” resets itself daily to the 24-hour cycle of the Earth’s rotation.

Optional: In a follow up study Siffre and several other participants, sponsored by NASA, ventured back underground remaining for a period of 6 months in a more comfortable cave in Texas.
This time, again investigating the passage of time without time cues, they observed something remarkable… that several people adjusted to a 48 hour rather than a 24-hour cycle during this longer period of isolation.
It became common for some participants to achieve cycles lasting forty-eight hours after long periods without natural light: They would have thirty-six hours of continuous activity followed by twelve to fourteen hours of sleep.

AO3: Research 3 into circadian rhythms
Campbell & Murphy (1998), in a bizarre experiment, shone bright lights onto the back of participants’ knees and were able to alter their circadian rhythms in line with the light exposure. It’s possible that the blood chemistry was altered and this was detected by the SCN.
This suggests that light detection in the body may be more complex than we might believe.
The fact that most blind people seem to be detecting light to reset their body clock also suggests cells other than rods and cones in our eyes may be responsible for light detection

Question 60

Menstrual cycles A01

Answer 60

The menstrual cycle is the regular natural change that occurs for women in the uterus and ovaries that make pregnancy possible and is governed primarily by endogenous hormonal changes. It is the time between the first day of a period and the day before the next period, which is on average 28 days. These changes can be altered exogenously by using hormonal birth control or by being exposed to the pheromones of other women.

• Step 1: An egg has not been fertilised and so hormone levels drop to cause menstruation
• Step 2: The pituitary gland starts to release FSH which prepares a new follicle to reach maturity in the ovary.
• Step 3: Once the follicle is developing oestrogen will be produced by the ovary which kick starts the thickening of the uterus walls.
• Step 4: LH is the next hormone to be released by the pituitary gland; this makes the egg detach from the ovary and begin travelling down to the uterus.
• Step 5: Progesterone is released from the ovary to maintain the thickness of the uterus lining in case the egg gets fertilised.
• Step 6: If the egg does not get fertilised progesterone and oestrogen levels will quickly drop and the egg will be flushed out and the cycle will begin again with a menstruation

Question 61

Menstrual cycles A01

Answer 61

The menstrual cycle is the regular natural change that occurs for women in the uterus and ovaries that make pregnancy possible and is governed primarily by endogenous hormonal changes. It is the time between the first day of a period and the day before the next period, which is on average 28 days. These changes can be altered exogenously by using hormonal birth control or by being exposed to the pheromones of other women.

• Step 1: An egg has not been fertilised and so hormone levels drop to cause menstruation
• Step 2: The pituitary gland starts to release FSH which prepares a new follicle to reach maturity in the ovary.
• Step 3: Once the follicle is developing oestrogen will be produced by the ovary which kick starts the thickening of the uterus walls.
• Step 4: LH is the next hormone to be released by the pituitary gland; this makes the egg detach from the ovary and begin travelling down to the uterus.
• Step 5: Progesterone is released from the ovary to maintain the thickness of the uterus lining in case the egg gets fertilised.
• Step 6: If the egg does not get fertilised progesterone and oestrogen levels will quickly drop and the egg will be flushed out and the cycle will begin again with menstruation

Question 62

Infradian rhythm A03

Answer 62

McClintok 10 year longitudinal study
- 29 women (20-35) history of irregular menstrual cycles
- sweat samples of 9 put on upper lip of other 20
- collected daily, sterilised
- worn 8 hours a day at least
- 68% experienced changes to cycles to be more similar to odour donor
- bad eco validity
+ study long term effects