unit 2 evaluation Flashcards
i.e approaches and biopsych
1
Q
evaluation of localisation and function in the brain
strengths
A
- brain scan evidence: Peterson et al used brain scans to show activity in wernkicks and broca. Tulving revealed semantic and episodic memories are located in different parts of the frontal cortext.
- neurological evidence: surgically removing or destroying airs of the brain. 44 OCD patients who had a cingulotomny at 32 week follow up 1/3 met successful response.
- case studies: unique cases of neurological damage such as phineas gage. personality changed frontal lobe responsible for regulating mood.
2
Q
evaluation of localisation and function in the brain
weaknesses
A
- contradictory research: Lashley suggested higher cognitive functions are not localised. removed between 10 and 50% of the cortex in rats learning a maze. no one area was more important. as learning requires every part of the cortex.
- neural plasticity. when the brain becomes damaged and function has been compromised or lost the rest of the brain is able to reorganise itself to recover the function. Lashley called this the law of equipotentiality other parts ot he brain chip in so the same action can be achieved. several documented cases of this.
3
Q
evaluation of plasticity and functional recovery
strengths
A
- practical application. understanding processes involved in plasticity contributed to neuro-rehabilitation. techniques include movement and electrical stimulation of the brain. at a point it the brain requires further intervention for functional recovery
- animal studies. Hubel and wiesel sewed one eye of a kitten shut and analysed the brain’s cortical responses. the area of the visual cortex associated continued to process information from the open eye. compensatory activity in the brain.
4
Q
evaluation of plasticity and functional recovery
limitations
A
- potential -ve consequences. maladaptive behavioural consequences. prolonged drug use result in poorer cognitive functioning and increased risk of dementia. 60 - 80% of amputees develop phantom limb syndrome due to reorganisation in the somatosensory cortex. not always beneficial.
- age ad plasticity relationship complex. functional recovery reduces with age. brain has a greater propensity for reorganisation in childhood as it constantly adapts to new experiences and learning. Bezzola et al demonstrated 40 years of golf training produced changes in the neural representation of movement in older people. does continue through life time.
- cognitive reserve. person’s educational attainment may influence how well the brain adapts. found the more time brain injury patients had spent in education the greater their chances of recovery.
5
Q
evaluation of split brain research into hemispheric lateralisation
strengths
A
- research shows laterlised brain functions. the left hemisphere is analytical and verbal (the analyser) and the right is adept at spatial tasks and music (the synthesiser). the right hemisphere can only produce basic words and phrases but contributed emotional content to language. distinction may be too simplified and several tasks associated with 1 hemisphere can also be carried out by the other.
- methodology. sperry used a carefully standardised procedure. participants stated at a fixed point with one eye. an image flashed up for 0.1 seconds so the patient had no time to move their eyes over the image. this allowed sperry to vary aspects of the basic procedure. well controlled procedure.
- started a debate about the nature of the brain. triggered a theoretical and philosophical debate about the nature of conscious and degree of communications. some suggest hemisphere are so functional different they represent a form of duality in the brain.
6
Q
evaluation of split brain research into hemispheric lateralisation
limitations
A
- generalisation. split brains patients are a very unusual sample of people. only 11 patients took part in all variations all had a history of seizures. this may have caused unique changes to the brain influencing the findings. the limits the extent to which the findings can be generalised to normal brains, reducing validity
- differences in hemispheric functions overstated. growing body of pop-psychological literature that oversimplifies and overstates the difference in functions between the 2 hemispheres. modern neuroscientists argue these distinctions are not all clear cut. may behaviours performed by one hemisphere can be performed by the other when required. the apparent flexibility of the 2 hemispheres suggests some of the conclusions drawn are too simplistic.
7
Q
evaluation of fMRI
A
- non invasive. unlike other scanning techniques does not rely on the use of radiation and is safe.
- it produces images with high spatial resolution showing detail by the millimetre. this means fMRI can provide a clear picture of how brain activity is localised.
- fMRI is expensive compared to other techniques and can only capture a clear image of a person if they stay still
- it has poor temporal resolution because of 5 second lag between initial neural activity and image. this means fMRI may not truly represent moment to moment brain activity
8
Q
evaluation of EEGs
A
- contributed to our understanding of the stages of sleep
- has extremely high temporal resolution. EEgs can detect brain activity at a resolution of a single millisecond.
- invaluable in diagnosing conditions such as epilepsy
- EEG produces a generalised signal from thousands of neurons. So it is difficult to know the exact source of neural activity. Cant distinguish between the activity of different but adjacent neurons.
9
Q
evaluation of ERPs
A
- ERPs are more specific than can be achieved using raw EEG data.
- they have excellent temporal resolution especially compared to fMRI
- lacks standardisation in methodology between studies. this makes it difficult to confirm findings in studies involving ERPs.
- background noise and extraneous material must be completely eliminated. this may not always be easy to achieve.
10
Q
post mortem evaluation
A
- Broca and Wernicke both relied on post mortem sutides.
- post mortem studies improve medical knowledge. they help generate hypotheses for further study.
- observed damage in the brain may not be linked to the deficits under review but to some other related trauma or decay.
- raise ethical issues of consent from the patient before death.
patients may not be able to provide informed consent.
11
Q
evaluation of circadian rhythms
strengths
A
- practical application to shift work. Shift workers experience a lapse of concentration around 6am so mistakes and accidents are ore likely, research suggested a link between shift work and poor health, with shift workers 3 time more likely to develop heart disease. thus research have economic implications.
- practical application to drug treatments. circadian rhythms coordinate the bodies basic processes with implications for pharmacokinetics.
12
Q
evaluation of circadian rhythms
limitations
A
- case studies and small sample sizes. use of small groups or single individual. participants not representative of wider population limiting meaningful generalisations. Siffre clock slower at 60. even when 1 person involved many factors prevent general conclusions
- poor control. participants deprived of natural light but still had artificial light assumed to have no effect. adjust circadian rhythm from 22 to 28 hours using dim lighting. artificial lighting confounding variable.
- individual differences. individuals vary from 13 to 65 hour cycles. some display natural preference for sleeping and rising early others vis versa. age effects sleep wake patterns. findings may not fully represent individual differences within population
13
Q
evaluation of infradian rhythms
A
- research on menstrual cycle shows evolutionary value. advantageous for females to menstruate together and become pregnant same time so offspring could be looked after collectively increasing survival. validity of this perspective produce competition for highest quality males lowing fitness of potential offspring. avoidance of synchrony would be adaptive evolutionary.
- limitation in methodology. factors that may change menstrual cycle as confounding variables. what we would expect to occur by chance. small sample, self reporting onset may be inaccurate. lack validity
- animal studies. role of pheromones of animal sexual behaviour well documented, evidence for the effect in humans is speculative and inconclusive
- practical application. SAD photo therapy stimulates strong light resetting melatonin levels. relieve symptoms in 60% if sufferers placebo effect of 30%. cast doubt on the value.
14
Q
evaluation of ultradian rhythms
A
- evidence support qualitatively different stages of sleep
monitored sleep patterns of 9 participants in sleep lav found evidence for stages of sleep. REM activity during sleep correlated with dreaming; brain activity varied according to how vivid the dreams were; when woken immediately they could accurately recall.
suggests REM sleep is a distinct ultraidan rhythm and is important component of the ultradian sleep cycle.
15
Q
evaluation of edogenous pacemakers
A
- research into SCN obscures other body clocks. body clocks (peripheral oscillators) are found in many organs and cells they are influenced by the SCN but act independently changing feeding patterns in mice altered circadian rhythms of cells in the liver by up to 12 hours, leaving SCN rhythm unaffected. many other complex influences.
- use of animals. hard to generalise findings because cognitive factors more significant in humans. ethics involved. exposed to great harm and potential risk. does benefits justify procedures used.
