Biopsychology AO3 Flashcards
Case study supporting localisation of function.
Phineas Gage.
When preparing to blast rock Gage dropped his tampering iron setting of the explosives hurling the rod into his left cheek exciting at the top taking a portion of his frontal lobe. Gage survived but was described as rude and quick-tempered - no longer Gage.
This suggests his Brocas area was damaged resulting in a personality change, the region that allows us to live and function was intact.
However, case study - cannot be generalised, was there any prior damage?
Strength of localisation of function.
Damaged areas of the brain have been linked to mental disorders.
Neurosurgery as treatment is a last resort, targeting specific areas.
E.g. Cingulotmy isolates the cingular gyrus (implicated in OCD). Found of 44 people 30% had a full response and 14% a partial.
Suggesting serious disorders may be localised.
However, as not everyone had a full response OCD may not be purely localised, a holistic approach may be more suitable.
Weakness of localisation of function.
Language may not be localised to only Broca and Wernicke area.
Advances in brain imaging techniques, mean neural processes can be studied with more clarity. Language function is distributed more holistically as so-called language streams have been identified across the cortex, regions in the high hemisphere and subcortical regions.
Strength of hemispheric lateralisation.
Research shows even in connected brains the hemispheres process information differently.
Fink et al (1996) found when ppts looked at global elements of an image (i.e. whole forest) regions of RH were more active but when focused on finer detail (i.e. individual tree) specific areas of the LH were dominant.
However, PET scans can give false results if chemical balances aren’t normal.
Lateralisation is likely adaptive (strength).
As it has evolved and been maintained likely due to value. It’s probable that it allows animals to perform two tasks simultaneously with greater efficiency Rogers et al. (2004) showed that chickens with a lateralised brain could find food while watching for predators whereas chickens, whose brain was not lateralised, couldn’t.
However, neural plasticity may also be adaptive, as there is a benefit for individuals (survival and reproductive) for brains not to be too fixed in structure in case of injury.
Weakness of hemispheric lateralisation
The concept of LH as an analyser and RH as a synthesiser may be wrong.
Nielsen et al analysed brain scans of over 1000 people and found no evidence of a dominant side, only that people use certain hemispheres for certain tasks (lateralisation).
Suggests the notion of right or left-brained people is wrong.
Furthermore, this study has high population validity.
Strength of Sperry’s research.
Research support.
Luck et al (1989) showed split brain ppts performed better on certain tasks, they were faster at identifying the odd one out in an array of similar objects than controls. This is likely as the LH cognitive strategies are watered down.
Limitation of Sperry’s research.
Casual relationships are hard to establish.
None of the ppts in Sperry’s control group had epilepsy, they were neurotypical. This is a major confounding variable as any differences may have been the result of epilepsy as opposed to the split-brain.
Ethical implications of Sperry’s research.
The trauma of the operation may mean patients didn’t fully understand the implications of what they were agreeing to. The repetitive testing may have been stressful over time.
Sperry’s patients may have felt obliged to continue once they had established a relationship with Sperry and fellow researchers. Furthermore, learning of one’s deficits under the strain of laboratory testing may not have been easy for some of the patients.
However, this doesn’t mean Sperry didn’t adhere to ethical guidelines, these were just negative consequences.
Limitation of neural plasticity.
Can have negative effects.
Ramachandran and Hirstein found that 60-80% of amputees had been known to develop phantom limb syndrome. These are unpleasant and painful, thought to be due to reorganisation in the somatosensory cortex as a result of limb loss.
Suggests new neural connections formed can actually have negative effects and impacts.
Strength of neural plasticity.
Plasticity may be a lifelong ability.
Bezzola et al demonstrate how hours of golf training produced changes in neural representations of movement in ppts. Using fMRI researchers observed increased motor cortex activity in the novice golfers, suggesting more efficient neural representations.
This shows neural plasticity can last our entire lifespan.
Practical application of research into neural plasticity.
Our understanding of plasticity has contributed to patient recovery after brain injuries. Suggests that a number of weeks of physiotherapy may be required to maintain improvements in functioning.
Suggest this research has contributed to real-world injuries and recovery.
However, doesn’t account for individual differences.
Strength of functional recovery.
Support from animal studies.
Hubel and Wiesel (1963) found an area of the visual cortex associated with shut-eye responses wasn’t ideal but continued to process information from the open eye.
Suggests the kitten’s brain made new connections to make up for the lack of visual information from the one eye.
However, there are significant ethical implications.
Real-world applicability of functional recovery.
Contributed to the field of neurorehabilitation. Understanding that axonal growth is possible, encourages new therapies to be tried.
Constraint-induced movement therapy is used with stoke patients, where they repeatedly practice using the affected body part with the unaffected restrained.
Showing that this research helps medical professionals with interventions.
Limitation of functional recovery.
Level of education may influence recovery rates.
Schneider (2014) found the more time in education the greater the chance of a disability-free recovery. 2/5 who achieved disability-free recovery had 16+ years of education compared to 10% who had 12 or under.
This suggests people who have insufficient disability-free recovery are less likely to achieve a full recovery.
