Studied by 1 person
when an environmental stressor is perceived (e.g. your friend jumps out to frighten you) the first thing that happens is the hypothalamus activates.
this triggers activity in the sympathetic branch of the autonomic NS (the ANS changes from resting state, parasympathetic branch, to sympathetic state).
at the same time, the adrenal gland releases adrenaline into the bloodstream.
this causes a series of changes in our body allowing us to fight/flight.
finally, once the threat/stressor has passed, your body returns to the parasympathetic NS and the physiological changes revert - its actions are antagonistic to the sympathetic system.
Lashley's research contradicts localisation he removed areas of the cortex (10-50%) in rats that were learning a maze. no area was proven to be more important than any other area in terms of the rats' ability to learn the maze. what affected the rats' learning was how much was removed. this weakens localisation as it implies a higher cognitive skill such as learning may be holistic (requires every part of the cortex)
Plasticity weakens localisation the brain is 'plastic' - it can change/repair itself. when the brain has become damaged and a particular function has been comprimised or lost, the rest of the brain appears able to reorganise itself in an attempt to recover the lost function. weakens localisation - suggests any part of the brain can do any function
plasticity may result in maladaptive changes Medina (2007) found that persistent use of drugs led to a dramatic loss in cognitive functioning. it also increases the risk of dementia later in life and strokes Hirstein (2008) found that up to 80% of amputees had experiences of phantom limb syndrome. for nearly all this was a pain sensation this shows that whilst plasticity can be good and help people, the fact our brain can change can also lead to negative consequences
plasticity reduces with age functional plasticity reduces with age. this means that it will be a lot harder for an older individual to repair their brain following trauma However, a study found that it can still change later in life: a study got elderly individuals to play 40 hours of golf, taking brain scans before & after. found that their brain had developed more grey matter in motor cortex so, whilst more difficult it is not impossible for the brain to change
expensive
can only capture a clear image if person stays perfectly still
poor temporal resolution as there's a 5-second time-lag behind the image on screen & the initial firing of neuronal activity
can only measure blood flow in the brain, it can't home in on the activity of individual neurons so it's difficult to tell exactly what kind of brain activity is being represented on screen
generalised nature of info received
poor spatial resolution: not useful for pinpointing the exact source of neural activity
doesn't allow researchers to distinguish between activities originating in different but adjacent locations
lack of standardisation in ERP methodology between diff research studies which makes it difficult to confirm findings
in order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated - not always easy to achieve
causation: observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay.
raise ethical issues of consent from patient before death; may not be able to provide informed consent due to their condition
difficult to generalise his findings split-brain patients were an unusual sample: only tested 11 people, all of whom had a history of epileptic seizures. however, his control group of 11 people were individuals who had a split-brain but no history of epilepsy - this is a problem because we don't know if Sperry's patients performance was due to the history of epilepsy or split-brain (he has 2 IV's) this weakens his study as we cannot draw any firm conclusions about hemisphere lateralisation from his study
Sperry overemphasised the differences between hemispheres modern neuroscientists argue that there is not such a distinct difference between the 2 hemispheres and that they can do most tasks when required (plasticity) in the normal brain the 2 hemispheres are in constant communication when performing everyday tasks, and many of the behaviours typically associated with 1 hemisphere can be effectively performed by the other when the situation requires it. this weakens Sperry as it suggests he may have exaggerated his findings.
supporting evidence Decoursey (2000) removed SCN from 30 chipmunks' brains. they then put them back into the wild. found that most of them were eaten by predators. this was because they had lost their typical sleep/wake pattern meaning they were awake when they should have been asleep. this supports SCN as primary pacemaker because without it they had no sleep/wake cycle.
generalisation issues study done on chipmunks, not humans therefore we can't be sure if SCN plays the same role in humans
ethics is harming/killing animals worth the knowledge gained?
generalisation issues studies of sleep/wake cycle involved a small group of ppts, or single individuals like Siffre. people involved may not be representative of winder pop - this limits the extent to which meaningful generalisations can be made. Siffre: case study of 1 man, can't say with confidence that his findings would be the same in everyone else. he can't even generalise himself as he retested himself years later & found a different finding. this weakens his study dramatically. (illustrates that, even when same person is involved, there are factors that vary which may prevent general conclusions being drawn)
validity of findings questionable due to poor control Siffre believed he was testing a free-running clock due to no natural light. however, he took a lamp in with him, and we now know that artificial light can have just the same effect as natural light. this means Siffre didn't test what he intended & we know little about the free-running clock.
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