BIOPSYCHOLOGY Flashcards
strengths of localisation of function in the brain
x3
support from brain scan evidence:
Peterson et al. used brain scans to show activity in Wernicke’s area during a listening task and in Broca’s area during a reading task, suggesting these areas of the brain have different functions. also, study of long-term memory by Tulving et al. revealed semantic and episodic memories are located in different parts of the frontal cortex. scientific evidence of localisation of function
support from neurological evidence:
Dougherty et al. reported on 44 OCD patients who had had a cingulotomy. At a 32 week follow up, 1/3 met the criteria for successful response to surgery and 14% for partial response. success of such procedures strongly suggests that symptoms and behaviours assoicated with serious mental disorders are localised
support from case studies:
Phineas Gage had a tamping iron through his cheek which removed part of his frontal lobe. His personality changed from someone who was calm and reserved to someone who was quick-tempered and rude. change in his temperament suggests the frontal lobe may be responsible for regulating mood
limitation of localisation of function of the brain
contradictory research:
work of Lashley suggests higher cognitive functions are not localised but distributed in a more holistic way in the brain. he removed between 10% and 50% of the cortex in rats learning a maze. no one area was more important than any other in terms of the rats’ ability to learn the maze. learning required every part of the cortex rather than particular areas suggesting learning is too complex to be localised and involves the whole of the brain
strengths of plasticity and functional recovery after trauma
x3
practical application:
understanding processes behind plasticity has contrubited to field of neurorehabilitation. techniques include movement therapy and electrical stimulation of brain to counter deficits to cognitive functioning experienced following a stroke. brain can fix itself to a point but needs intervention to be successful
support from animl studies:
Hubel & Wiesel sewed one eye shut of a kitten. found the visual cortex associated with the shut eye continued to process infromation from the open eye. demonstrates how loss of function leads to compensatory activity in the brain
support for link between age and recovery:
Teuber found 60% of brain damaged soldiers aged under 20 recovered from movement and visual problems but only 20% of those over 26 did
limitations of plasticity and functional recovery after trauma
x2
negative consequences:
ability to rewire itself can have maladaptive behavioural consequences e.g prolonged drug use can result in poorer cognitive functioning and increase risk of dementia (Medina). also 60-80 of amputees develop painful phantom limb syndrome due to reorganisation in somatosensory area. processes involved in functional recovery may not always be beneficial
relationship between age and plasticity is complex:
functional plasticity tends to reduce withh age. however, Bezzola et al. demonstrated how 40 hours of golf training produced changes in neural representation of movement in ppts aged 40-60. neural plasticity does continue throughout our lifetime
strengths of Sperry’s split-brain research into hemispheric lateralisation
x2
methodology:
carefully standardised procedure of presenting visual info to one hemispheric field at as time was ingenious. ppts stared at a fixed point with one eye and an image was flashed up for 0.1 seconds so had no time to move their eyes over the image and spread the info across both sides of the visual field or of the brain. allowed Sperry to vary aspects of the basic procedure and ensure only one hemisphere received info at a time
Sperry’s work started a debate about the nature of the brain:
work triggered a debate about the degree of communication between the 2 hemisphers in everyday functioning. Pucetti suggested the hemispheres are so functionally different they represent a form of duality in the brain. others argued the 2 hemispheres are highly integrated and work together in most tasks. value of his work is in promtping this complex debate
limitations of Sperry’s split-barin reserach into hemispheric lateralisation
x2
issues with generalisation:
many researchers have said these findings cannot be widely accepted as split-brain patients are such an unsual sample of people. only 11 patients took part in all variations and all had a history of seizures which may have caused unique changes in the brain that influenced the findings. limits extent to which findings can be generalised to normal brains
differences in hemispheric functions may be overstated:
legacy of Sperry’s work is lierature that oversimplifies and overtstates the difference in fuction between the 2 hemispheres (right is synthesiser and left is analyser). modern neuroscientists argue these distinctions are not at all clear-cut and that many behaviours that are typically associated with 1 hemisphere can be performed by the other when situations require. flexibility of the 2 hemispheres suggests some of the conclusions drawn by Sperry may be too simplistic
strength and limitation of fMRI
non-invasive and detailed:
unlike other scanning techniques fMRI does not rely on the use of radiation and is safe. another strength is that it produces images with high spatial resolution, showing detail by the mm. can provide a clear picture of how activity is localised
expensive and poor temporal resolution
expensive compared to other techniques and can only capture a clear image if the perrson stays still. also it has poor temporal resolution due to 5-second lag between initial neural activity and image. may not truly represent moment-to-moment brain activity
strength and limitation of EEG
invaluable in diagnosing conditions such as epilepsy and has contributed to our understanding of the stages of sleep. extremely high temporal resolution so can detect brain activity at a resolution of a single millisecond
info received from thousands of neurons and difficult to know the excat source of neural activity
strength and limitation of ERPs
more specific measurement of neural processes than EEG and also have excellent temporal resolution
lack of standardisation in methodology between studies so difficult to confirm findings in studies involving ERPs. also background noie and other extraneous material must be completely eliminated which isn’t easy to achieve
strength and limitation of post-mortems
provided the foundation for understanding the brain as Broca and Wernicke both relied on post-mortem studies. improve medical knowledge and help generate hypotheses for further study
causation is an issue as observed damage to the brain may not be linked to deficits under review but to some other related trauma. also raise ethical issues as pateints may not be able to provide informed consent before death e.g HM
strengths of circadian rhythms
x2
research has a practical application to shift work:
Boivin et al. found shift workers experience a lapse of concentration around 6am (a circadian trough) so mistakes and accidents are more likely. research also suggests a link between shift work and poor health, with shift workers 3x more likely to develop heart disease (Knutsson). research into sleep/wake cycle may have economic implications in terms of how to best manage worker productivity
practical application to drug treatments:
research shows there are times during the day or night when drugs are more effective. guidelines have been developed for the timing of dosing including treatments for cancer and epilepsy. research into circadian rhythms may have real-life medical benefits
limitations of circadian rhythms
x2
use of case studies and small samples in studies:
studies of sleep/wake cycle often use small groups of ppts e.g Aschoff & Weaver or even single individuals (Siffre). Siffre observed that his internal clock ticked much more slowly at 60 than when he was younger, suggesting that when the same person is involved, there are factors preventing general conclusions being drawn. ppts may not be representative of the wider population and this limits making meaningful generalisations
poor control in research studies:
ppts deprived of natural light still had access to artificial light e.g Siffre had a lamp turned on from when he woke up to when he went to bed as artifical light was assumed to have no effect on free-running rhythms. Czeisler et al. adjusted ppts from 22 to 28 hours using dim lighting, showing artificial light does have some influence. researchers may have ignored an important confounding variable in ciracdian rhythm research
strengths of infradian and ultradian rhythms
x3
evidence supports qualitatively different stages of sleep:
Dement & Kleitman monitored the sleep patterns of nine participants in a sleep lab and found evidence for stages of sleep, specifically REM sleep. REM activity during sleep correlated with dreaming, brain activity varied according to how vivid dreams were and ppts woken during dreams had accurate recall. study suggests that REM sleep is a distinct ultradian rhythm and an important component of the sleep cycle
research into SAD has practical applications:
an effective treatment for SAD is phototherapy, a lightbox that stiulates strong light in the morning and evening (to reset melatonin levels). relieves symptoms in up to 60% of sufferers (Eastman et al.) so research contributes to treating patients.
also, Blakemore found using phototherapy for a few hours on waking which was very similar to natural light relieved Pat Moore’s symtpoms within a few days of beginning therapy
limitation of infradian and ultradian rhythms
methodology used in synchronisation studies:
many factors that may change a woman’s menstrual cycle and act as confounding variables e.g changes in diet. so any pattern of synchronisation is what we would expect to occur by chance. also research involves small samples of women and relies on them self-reporting onset of their own cycle (may be inaccurate). suggests important aspects of synchronisation studies may be inaccurate
limitations of endogenous pacemakers and exogenous zeitgebers
x4
research into the SCN may obsure other body clocks: body clocks (peripheral oscillators) are found in many organs and cells e.g lungs and are highly influenced by the actions of the SCN but can also act independently. Damiola et al. showed how changing feeding patterns in mice altered circadian rhythms of cells in the liver for up to 12 hours whilst leaving the rhythm of the SCN unaffected. suggests there may be other complex influences on the seep/wake cycle apart from the SCN
use of animals:
issue in generalising findings from animal studies as cognitive factors may be more signifcant in humans. more disturbing issue is the ethics of such research e.g Docursey et al. as animals were exposed to great harm and potential risk when they returned to their natural habitat. debate as to whether what we learn from research justifies averisve procedures involved
influence of exogneous zeitgebers may be overstated:
Miles et al. note the case of a man blind from birth with a circadian rhythm of 24.9 hours. his sleep/wake cycle could nt adjust to social cues so he took sedatives at night and stimulants in the morning to align with 24hour world. also, studies of individuals who live in Artic regions where sun doesn’t set in summer show normal sleep patterns despite prolonged exposure to light. both suggest there are occasions when exogenous zeitgebers have little influence over our internal rhythm
methodological issues in exogenous zeitgebers research:
Campbell & Murphy’s study is yet to be replicated and is criticised as there may have been some light exposure to ppts’ eyes (major confounding variable). also, isolating one exogenous zeitgeber (light) doesn’t give insight into many other zeitgebers that influence the sleep/wake cycle. suggests some studies may underplay or ignore the way in which different exogenous zeitgebers interact
