Biopsychology Flashcards
Discuss the extent to which brain functions are localised. Refer to evidence in your answer.
A01
Localistation versus holistic theory:
Broca and Wernicke discovered that specific areas of the brain are associated with particular physical and psychological functions.
Holistic theory - all parts of the brain were involved in the processing of thought and action.
Cortical specialisation
If a certain area of the brain becomes damaged through illness, the function associated with that area will also be affected.
Hemispheres of the brain and the cerebral cortex:
Lateralisation - some physical or psychological functions are controlled by a particular hemisphere.
Cereberal cortex is what distinguishes us from animals.
The motor, Somatosensory, visual and auditory centres:
Fontal lobe - motor area, damage to this area of the brain may result in a loss of control over fine movements.
Parietal lobes - somatosensory area, Separated from the motor area by the central sulcus. This is where sensory info from the skin is represented. More somatosensory area = more sensitivity.
Occipital lobe - visual area. Damage to the left hemisphere may result in blindness in part of the right visual fields of both eyes.
Temporal lobe - auditory area, speech-based info.
Language area of the brain:
Language is restricted to the left side of the brain.
Brocas area = small area in the left frontal lobe responsible for speech production.
Brocas Aphasia = speech that is slow, laborious and lacking in fluency.
Wernicke was describing patients who had trouble understanding what they said.
Speech was fluent but meaningless.
Wernicke’s area = left temporal lobe responsible for language comprehension -> result in Wernicke’s aphasia.
A02
Brain scan evidence of localisation:
Petersen - Used brain scans to demonstrate how Wernicke’s area was active during a listening task and Broca’s area was active during a reading task -> suggests areas of brain have different functions.
Tulving - semantic and episodic memories reside in different parts of the prefrontal cortex.
Neurosurgical evidence:
The practice of surgically removing or destroying areas of the brain to control aspects of behaviour.
In extreme cases of OCD and depression this may be used.
Dougherty - reported on 44 OCD patients who had undergone a cingulotomy.
after 32 weeks, 1/3 had met criteria for successful response and 14% for partial response.
Procedures like this strongly suggest that symptoms and behaviours associated with mental disorders are loaclised.
The case of Phineas Gage
Discuss research into plasticity of the brain including functional recovery
A01
Brain plasticity:
The brain has the ability to change throughout life.
During infancy the brain develops many synaptic connections, as we age, rarely used connections are deleted and frequently used connections are strengthened - Synaptic pruning.
More recent research suggests that changes in the brain can happen at any time and not just during infancy as a result of learning new experiences.
Research into plasticity:
Maguire - studied the brains of London Taxi drivers and found significantly more grey matter in the posterior hippocampus than in the matched control group.
This part of the brain is associated with the development of spatial and navigational skills.
The longer they had been in the job, the more pronounced was the structural difference.
‘The Knowledge’ alters their brain connections.
Draganski - imaged the brains of medical students three months before and after their final exams.
Learning-induced changes were seen in the posterior hippocampus and parietal cortex.
Mechelli - Found a larger parietal cortex in the brains of people who were bilingual.
What happens in the brain during recovery?:
Secondary neural pathways that would otherwise not be used to carry out certain functions are activated to enable functioning to continue.
axonal sprouting - the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways.
Reformation of blood vessels.
Recruitment of homologous areas on the opposite side of the brain to perform specific tasks. An example would be if Broca’s area was damaged on the left side of the brain, the right-sided equivalent would carry out its functions.
A02
Practical application:
Understanding the processes involved in plasticity has contributed to the field of neurorehabilitation.
Spontaneous recovery tends to slow down after a number of weeks so forms of physical therapy may be required to maintain improvements in functioning.
Movement therapy and electrical stimulation of the brain to counter the deficits in motor and/or cognitive functioning.
Shows that although the brain may be able to fix itself to a point, this process requires further intervention if it is to be completely successful.
Age and plasticity:
Functional plasticity tends to reduce with age.
The brain has a greater potential to reorganise during childhood as we are constantly learning new experiences.
Bezzola et al -> demonstrated how 40 hours of golf training produced changes in the neural representation of movement in participants aged 40-60.
Researchers observed reduced motor cortex activity in the novice golfers compared to a control group, suggesting more efficient neural representations after training.
Shows that neural plasticity does continue through out the lifespan and provides support for the theory of plasticity.
The concept of cognitive reserve:
A person’s educational attainment may influence how well the brain functionally adapts after injury.
Schneider et al -> discovered that the more time brain injury brain injury patients had spent in education (indication of their cognitive reserve) the greater their chances of a disability-free recovery.
2/5 of patients studied who achieved DFR had more than 16 years’ education compared to about 10% of patients who had less that 12 years education.
Discuss split-brain research.
A01:
Hemispheric lateralisation:
The ability to produce and understand language is controlled by the left hemisphere -> language is subject to hemispheric lateralisation.
Sperry and his colleagues investigated whether other processes in the brain are also subject to hemispheric leteralisation.
Split-brain studies:
The participants were all split-brain patients - their corpus callosum had been severed.
The main communication line between the two hemispheres was severed.
Allowed Sperry to observe the extent to which hemisphere performs what task.
An image or word would be projected to a patient’s right visual field and the same, or different image could be projected to the left visual field.
Describing what you see:
When a picture of an object was shown to a patient’s right visual field, the patient could easily describe what was seen.
If the same object was shown to the left visual field, the patient could not describe what was seen. Typically reported that there was nothing there.
Language is processed in the left hemisphere and thus the left visual field (processed by the right hemisphere)
has a lack of language centres.
Recognition by touch:
Although patients could not attach verbal labels to objects projected in the left visual field, they were able to select a matching object from a grab bag of different objects using the left hand.
The left hand was also able to select an object that was most closely associated with an object presented to the left visual field.
The patient could understand what the object was using the right hemisphere.
Composite words:
If two words were presented simultaneously, one on either side of the visual field, the patient would write with their left hand what was seen on the left visual field and say the word that was presented to the right visual field (processed by the left hemisphere).
Matching faces:
The right hemisphere also appeared dominant in terms of recognising faces.
When asked to match a face from a series of other faces, the picture processed by the right hemisphere was consistently selected, whilst the picture presented to the left hemisphere was consistently ignored.
When a composite picture made up of two different halves of a face was presented the left hemisphere dominated in terms of verbal description whereas the right hemisphere dominated in terms of selecting a matching picture.
A02:
Theoretical basis:
Sperry’s work prompted a theoretical and philosophical debate about the degree of communication between the two hemispheres in everyday functioning and the nature of consciousness.
Pucetti -> suggested that the 2 hemispheres are so functionally different that they represent a form of duality in the brain - in effect, we are all 2 minds.
In contrast, other researchers have argued that, the 2 hemispheres form a highly integrated system and are both involved in most everyday tasks.
Issues with generalisation:
Many researchers have urged caution in their widespread acceptance, as split-brain patients constitute such an unusual sample of people.
Only 11 participants and all of whom had a history of epileptic seizures.
These seizures may have caused unique changes in the brain that may have influenced the findings.
Some participants had experienced more separation of the 2 hemispheres as part of their surgical procedures.
The control group that Sperry used was made up of 11 people with no history of epileptic seizures and this is an inappropriate control.
Differences in function may be overstated:
One legacy of Sperry’s work was a growing body of pop-psychological literature that overstates and oversimplifies the functional distinction between the 2 hemispheres.
Modern neuroscientists would would contend that the actual distinction between the 2 hemispheres is messier than the labels that have been used.
In the normal brain, the 2 hemispheres are in constant communication when performing tasks.
Many of the behaviours typically associated with one hemisphere can be effectively performed by the other when the situation requires it.
Describe and evaluate scanning techniques as a way of investigating the brain.
A01
fMRI:
Detects changes in the blood oxygenation and flow that can occur as a result of neural activity in specific parts of the brain.
When a brain part is more active more oxygen is consumed to satisfy demand, blood flow is directed to active area.
Produces 3D images showing which parts of the brain are involved in particular mental processes.
Important implications for our understanding of localisation.
EEG:
Measure electrical activity within the brain via electrodes that are fixed to an individual’s scalp using a skull cap.
The scan recording represents the brainwave patterns that are generated from the action of millions of neurons, providing an overall account of brain activity.
Often used as a diagnostic tool.
May indicate neurological abnormalities.
ERPs:
Within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists.
All extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to a specific task or specific stimulus.
What remains are ERPs - types of brainwave that are triggered by particular events.
Post-mortem examinations:
Analysis of a person’s brain following their death.
A02
fMRI:
Strengths - Does not rely on the use of radiation, virtually risk-free, non-invasive, straightforward to use, produces images that have very high spatial resolution, provides a clear picture of how brain activity is localised.
Wesknesses - Expensive, can only capture a clear image if the person stays still, poor temporal resolution, can only measure blood flow in the brain, cannot focus on individual neurones.
EEG:
Strengths - Proved invaluable in the diagnosis of epilepsy, contributed to our understanding in the stages of sleep, high temporal resolution, can accurately detect brain activity at a resolution of a single millisecond.
Weaknesses - The EEG is not useful for pinpointing the exact source of neural activity, does not allow researchers to distinguish between activities originating in different but adjacent locations.
ERP:
Strengths - bring more specificity to the measurement of neural processes, excellent temporal resolution, researchers have been able to identify many types of ERPs and describe the precise role of these in cognitive functioning.
Weaknesses - Lack of standardisation in methodology between different research studies, background noise and extraneous material must be completely eliminated which isn’t very easy.
Post-mortems:
Strengths - Vital in providing a foundation for early understanding of key processes in the brain, Broca and Wernicke relied on this technique before neuroimaging was possible, improve medical knowledge.
Weaknesses - Causation is an issue, observed damage to the brain may not be linked to the deficits under review, raise ethical issues of consent, patients may not be able to give informed consent.
Discuss research into circadian rhythms.
A01
Biological rhythms:
Biological rhythms exert an important influence on the way in which body systems behave.
Biological rhythms are governed by endogenous pacemakers (internal biological clocks) and exogenous zeitgebers (external changes in the environment).
Ultradian rhythms - occur many times during the day.
Infradian rhythms - Take longer than a day to complete.
Circadian rhythms - last around 24 hours: sleep/wake cycle and core body temp.
Core body temp:
Evidence suggests that body temp may have an effect on our mental abilities: the warmer we are, the better our cognitive performance,.
Folkard et al -> demonstrated how children who had stories read to them at 3pm showed superior recall and comprehension after a week compared to those who heard the same stories.
Gupta -> Found improved performance on IQ tests when ppts were assessed at 7pm rather than at 2pm or 9am.
Sleep/wake cycle:
The effect of daylight has a significant effect on how we feel in the morning and at night - an important exogenous zeitgeber.
What would happen without the influence of environmental stimuli like daylight?
Siffre’s cave study:
Siffre spent 2 months in a cave, deprived of exposure to natural light and sound but with access to adequate food and drink.
He re-surfaced in September, believing it was mid-August.
Spent 6 months in another cave.
Findings - his ‘free-running’ biological rhythm settled down to one that was just beyond the usual 24 hours though he did continue to fall asleep and wake up on a regular schedule.
Other studies:
Aschoff and Rutger:
Convinced a group of ppts to spend 4 weeks in a WWII bunker deprived of natural light.
All ppts displayed a circadian rhythm of between 24 and 25 hours.
These 2 studies suggest that the ‘natural’ sleep wake cycle may be longer than 24 hours but that it is entrained by exogenous zeitgebers associated with our 24-hour day.
Contradictory evidence:
Folkard: studied a group of 12 ppts who agreed to live in a dark cave for 3 weeks.
They retired to bed when the clock said 11:45 and woke when it said 7:45.
The researchers gradually sped up the clock so the 24 hour day only lasted 22 hours.
Findings - only one ppt was able to comfortable adjust to the new regime. This would suggest the existence of a strong free-running circadian rhythm that cannot easily be overridden by changes in the environment.
A02
Practical application to shift work:
Given researchers better knowledge into the adverse consequences that can occur as a result of the disruption of circadian rhythms.
Night workers experience a period of reduced concentration around 6am meaning mistakes and accidents are more likely.
There may also be a relationship between shift work and poor health.
Shift workers are 3 times more likely to develop heart disease which may in part be due to the stress of adjusting to different sleep/wake patterns and the lack of poor quality sleep during the day.
Research into sleep/wake cycle may have economic implications in terms of how to best manage worker productivity.
Practical application to drug treatments:
Circadian rhythms co-ordinate a number of the body’s basic processes - has an effect on pharmacokinetics - the action of drugs on the body and how well they are absorbed.
Research has revealed that there are certain peak times during the day or night when drugs are likely to be at their most effective.
Development of guidelines to do with the timing of drug dosing for a whole range of medication.
Use of case studies and small samples/poor control in studies:
The people involved may not be representative of the wider population and this limits the extents of generalisations.
In 1999, Siffre observed, at the age of 60, that his internal clock ticked much more slowly than when he was a young man - shows that even when the same person is involved, there are factors that vary which may prevent general conclusions being drawn.
Ppts still had access to artificial light - it was assumed that artificial light would have no effect on the biological rhythm.
However, Czeisler, was able to adjust ppts circadian rhythms from 22 to 28 hours using dim lighting.
The use of light may be analogous to ppts taking a drug that resets their biological clock.
Discuss research into infradian and ultradian rhythms.
A01: Infradian rhythms
The menstrual cycle:
Governed by monthly changes in hormone levels which regulate ovulation.
The cycle = the time between the first day of the period to the day before her next period.
Typical cycle takes 28 days
Rising levels of oestrogen cause the ovary to develop an egg and release it.
After ovulation, progesterone helps the womb lining grow thicker.
If pregnancy doesn’t occur, the womb lining is shed.
Research study:
The menstrual cycle in endogenous , evidence suggests that it may be influenced by exogenous factors - e.g the cycles of other women.
Stern and McClintock -> involved 29 women with a history of irregular periods. Samples of pheromones were gathered from 9 women at different stages of their cycles. The armpit pads were frozen and rubbed on the upper lip of the other ppts. On day 1, pads from the start of the cycle were applied to all 20 women, on day 2 they were all given a pad from the second day and so on.
Findings - 68% of women experienced changes to their cycle which brought them closer to the cycle of their ‘odour donor’.
Seasonal affective disorder (SAD)
Depressive disorder which has a seasonal pattern of onset.
Symptoms: persistent low moods, lack of activity and lack of interest in life.
Symptoms are triggered during the winter months when the number of daylight hours are shorter.
SAD is a circannual rhythm but can also be classed as a circadian rhythm and may be due to the disruption of the sleep/wake cycle.
It is thought that the hormone melatonin is implicated in SAD.
During the night, the pineal gland secretes melatonin until dawn when there is an increase in light.
During winter, the lack of light in the morning means this secretion process continues for longer.
Has an effect on the serotonin production in the brain.
A01: Ultradian rhythms
The sleep cycle:
Each of the stages in the sleep cycle is characterised by a different level of brainwave activity.
Stage 1 and 2: Light sleep where the person may be easily woken. At the beginning of sleep, brainwave patterns start to become slower and rhythmic.
Stage 3 and 4: Involves delta waves which are slower still and have a greater amplitude than earlier wave patterns. This is deep sleep and is difficult to wake someone.
Stage 5: REM sleep, the body is paralysed but brain activity speeds up significantly. Research has suggested that REM activity during sleep is highly correlated with the experience of dreaming.
A02
Evolutionary basis of the menstrual cycle:
For our ancestors it may have been advantageous for females to menstruate together and therefore fall pregnant around the same time.
New borns could be cared for collectively within a social group, increasing the chances of survival.
Schank -> argued that if there were too many females cycling together within a social group, this would produce competition for the highest quality male.
From this point of view, the avoidance of synchrony would appear to be the most adaptive evolutionary strategy and therefore naturally selected.
This calls into question the validity of the evolutionary perspective.
Evidence supports the idea of distinct stages of sleep:
Landmark study by Dement and Kleitman -> monitored the sleep patterns of nine adult participants in a sleep lab.
Brainwave activity was measured using EEG and the researchers controlled for the effects of caffeine and alcohol.
REM activity during sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were, and ppts woken during dreaming reported very accurate recall of their dreams.
Replications have noted similar findings.
Small size of original sample has been criticised.
Study suggests that REM sleep is an important component
Methodological limitations in synchronisation studies:
Commentators argue that there are many factors that may effect change in a woman’s menstrual cycle, including stress, changes in diet, etc, that might act as confounding variables.
Any supposed pattern of synchronisation is no more than would have been expected to occur by chance.
Research typically involves small samples of women and relies on self-report techniques.
Other studies failed to find any evidence of menstrual synchrony.
Discuss the effect of endogenous pacemakers and exogenous zeitgebers on the sleep/wake cycle.
A01: Endogenous pacemakers
The suprachiasmatic nucleus (SCN):
Tiny bundle of nerve cells found in the hypothalamus in each hemisphere of the brain
One of the primary endogenous pacemakers in mammalian species and is influential in maintaining circadian rhythms.
The SCN lies just above the optic chiasm.
Receives info about light directly from this structure and continues even when our eyes are closed, enabling the biological clock to adjust to changing patterns of daylight whilst we are sleep.
The SCN passes the info on day length and light that it receives onto the pineal gland.
During the night, the pineal gland increases production of melatonin - a chemical that induces sleep and is inhibited during periods of wakefulness.
Melatonin has also been suggested as a causal factor in SAD.
Animal studies and the SCN:
DeCoursey -> destroyed the SCN connections in the brains of 30 chipmunks who were then returned to their natural habitat and observed for 80 days.
The sleep/wake cycle of the chipmunks disappeared and by the end of the study a significant proportion of them had been killed by predators (being awake when they normally wouldn’t have been).
Ralph et al -> bred ‘mutant’ hamsters with a 20-houur sleep/wake cycle.
When SCN cells from the foetal tissue of mutant hamsters were transplanted into the brains of normal hamsters, their sleep/wake cycle defaulted to 20-hours.
Both of these studies emphasise the role of the SCN in establishing and maintaining the circadian sleep/wake cycle.
A01: Exogenous zeitgebers
External factors in the environment that reset our biological clocks through entrainment.
We have seen that, in the absence of external cues, the free running biological clock that controls the sleep/wake cycle continues to tick in a cyclical pattern.
Thus, sleeping and wakefulness would seem to be determined by an interaction of internal and external factors.
Light:
Light has an indirect influence on key processes in the body that control functions such as hormone secretion and blood circulation.
Campbell and Murphy -> demonstrated that light may be detected by skin receptors on the body even when the same info is not received by the eyes.
15 ppts were woken at various times and a light was shone at the back of their knees.
Researchers managed to produce a deviation in the ppts usual sleep/wake cycle of up to 3 hours.
Suggests that light is a powerful exogenous zeitgeber that need not necessarily rely on the eyes to exert its influence on the brain.
Social cues:
Infants are seldom on the sleep/wake cycle as the rest of the family.
The initial sleep/wake cycle is random.
At about 6 weeks of age, the circadian rhythms begin and by about 16 weeks, most babies are entrained.
Schedules imposed by parents are likely to be a key influence.
Research aslo suggests that adapting to local times for eating and sleeping, is an effective way of entraining circadian rhythms and beating jet lag when travelling long distances.
A02
Beyond the master clock:
Research has revealed that there are numerous circadian rhythms in many organs and cells of the body - peripheral oscillators.
These peripheral clocks can act independently.
Damiola -> demonstrated how changing feeding patterns in mice could alter the circadian rhythms of cells in the liver by up to 12 hours, whilst leaving the rhythm of the SCN unaffected.
Suggests that there may be many other complex influences on the sleep/wake cycle, side from the SCN.
Ethics in animal studies:
Hard to generalise findings on sleep/wake cycle of animals to humans.
A disturbing issue is the ethics involved in DeCoursey’s study.
The animals were exposed to considerable harm, and subsequent risk, when they were returned to their natural habitat.
Whether what we learn from investigations such as these justifies the aversive procedures involved is a matter of debate.
Influence of exogenous zeitgebers is overstated:
Miles et al -> Recounted the story of a young man who was blind from birth with a circadian rhythm of 24.9 hours.
Despite exposure to social cues, his sleep/wake cycle could not be adjusted, and consequently, he had to take sedatives at night and stimulants in the morning to keep in pace with the 24-hour world.
Studies of individuals who live in arctic regions show normal sleep patterns despite the prolonged exposure to light.
Both these examples suggest there are occasions when exogenous zeitgebers may have little bearing on our internal rhythm.
Furthermore, there are methodological issues with Campbell and Murphy’s study.
Their findings are yet to be replicated.
Limited light exposure to ppts eyes - a major confounding variable.
Isolating one exogenous zeitgeber in this way does not give us insight into the many other zeitgebers that influence the sleep/wake cycle, and the extent to which these may interact.
