Evaluation : Biopsychology Flashcards
What is a strength of the research into the localisation of function?
(neurosurgery)
Research support from Neurosugery
Lobotomies used to be common practice.
- Surgically removing or destroying parts of the frontal lobe.
- Brutal but often effective.
- Controversial still used today
Dougherty et al. (2002)
- Reported on 44 patients with OCD underwent a cingulotomy
- 32 week follow up 1 third showed a successful response.
🡪 Success suggests function is localised.
What is strength of localisation of the function?
(Case study evidence)
Case study Evidence
Lots of case study evidence to support the theory of localisation
- Gage was caught in an explosion which resulted in a meter length pole being hurled through his head and tearing out most of his frontal lobe.
- Gage survived but…
Became short tempered, rude and aggressive.
Suggests that the frontal lobe may be responsible for regulating mood - supports localisation.
What is a strength of the research into localisation?
Research support from brain scans
There is plenty of supporting evidence for the localisation of neurological function, particularly in language and memory
- For example Peterson et al. (1988) 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. Suggesting that these areas have different functions.
- Similarly, a study of long-term memory by Tulving et al. (1994) revealed that semantic and episodic memory reside in different parts of the prefrontal cortex.
Such research, which is conducted using highly sophisticated and objective methods to measure activity in the brain provide sound scientific evidence for the localisation of brain function.
What is a counterpoint to the strength of research into localisation?
Counterpoint: support for a hollistic theory
Karl Lashley (1950) challenges the idea of localization of function.
Lashley removed between 10% and 50% of the cortex in rats that were learning a route through a maze.
- No area was proven to be more or less important than another in terms of being able to learn the route.
- The process of learning appears to require the entire cortex.
- Suggests that higher order processes such as learning are distributed in a more holistic way.
What is a weakness of the localisation of the function?
Language Localisation is questioned
- However, although there is evidence from case studies to support the function of the Broca’s area and Wernicke’s area, more recent research has provided contradictory evidence.
- Dronkers et al. (2007) conducted an MRI scan on Tan’s brain, to try to confirm Broca’s findings.
- Although there was a lesion found in Broca’s area, they also found evidence to suggest other areas may have contributed to the failure in speech production.
These results suggest that the Broca’s area may not be the only region responsible for speech production and the deficits found in patients with Broca’s aphasia could be the result of damage to other neighbouring regions.
What is a strength of Hemisphereic laterialisation?
Strength : laterlisation in the normal brain
Even in a normal brain the two hemispheres process information differently.
- Fink et al. (1996) used PET scans to identify which brain areas were active during a visual processing task.
- When asked to attend to global elements 🡪 RH active.
- When asked to focus on detail 🡪 LH active.
This suggests that, at least for visual processing, hemispheric lateralisation is a feature of the normal brain as well as the split brain
What is a weakness of Hemispheric laterilisation?
Limitation : oversimplified- one brain
A limitation is that some aspects of lateralisation theory may be oversimplified.
- There may be different functions in the RH and LH, but research suggests people do not have a dominant side of their brain which creates a different personality.
- Nielsen et al analysed brain scans from over 1000 people and found that people used certain hemispheres for certain tasks, but there was no evidence of a dominant side, i.e. not artist’s/mathematician’s brain.
This suggests that the pop-psychology notion of right- or left-brained people is incorrect.
What is a weakness of the split brain research?
Limitation : Generlisation issues
One limitation of Sperry’s research is that causal relationships are hard to establish.
- The behaviour of Sperry’s split brain patients was compared to a neurotypical group, however an issue is that non of the participants in the control group had epilepsy.
- This is a major confounding variable, as any differences that were observed between the two groups may be the result of the epilepsy rather than the split brain.
This means that some of the unique features of the split-brain participants’ cognitive abilities might have been due to their epilepsy.
What is another weakness of the split brain research?
Limitation : Ethical issues
- On the one hand the patients had already had their corpus collosum cut by the time they came to Sperry’s attention and so were not deliberately harmed. In addition, all procedures were explained to the split-brain patients in advance of their involvement and their full informed consent was obtained. Sperry’s patients would have had the option of not taking part at this point and therefore their participation was voluntary.
- Having said that, it is possible that the trauma of the operation meant that the patients did not fully understand the implications of what they were agreeing to. They were subject to repeated testing over a lengthy period (years in some cases), and this may have been stressful over time. Furthermore, It is plausible that Sperry’s patients, having been involved in the first few studies, felt obliged to continue once they had established a relationship with Sperry and his fellow researchers. Finally, learning of one’s deficits under the strain of laboratory testing may not have been easy for some of the patients.
This suggests that although Sperry did not intend to harm the split-brain patients, there may have been negative consequences associated with their involvement. For this reason, it is difficult to say, on balance, that the split-brain studies were ethical, even though Sperry probably observed ethical guidelines.
What is a limitation of plasticity and functional recovery?
Limitation - negative plasticity
One limitation of the brain’s ability to rewire itself is that it may have negative behavioural consequences.
- Long term drug use leads to poor cognitive functions and increased risk of dementia.
- 60-80% of amputees have been known to develop phantom limb syndrome due to cortical reorganisation in the somatosensory cortex. (Ramachandran and Hirstein, 1998)
This suggests that the brain’s ability to adapt to damage is not always beneficial.
What is a strength of plasticty and functional recovery?
Strength - Age and plastcity
One strength of the brains ability to adapt and rewire itself is that is does not always sharply decline with age.
- Bezzola et al. (2012) demonstrated how 40hours of golf training produced changes in the neural representations of moving 40-60 year olds.
- fMRIs showed increased motor cortex activity in the novice golfers compared to the control group.
- Suggests more efficient neural representations after training.
This shows that neural plasticity can continue throughout the life span.
What is a strength of plastcity and functional recovery?
Strength : real world application
Understanding the processes involved in plasticity has contributed to the field of neurorehabilitation.
- Following illness or injury to the brain, spontaneous recovery tends to slow down after a number of weeks.
- Due to this, a form of physical therapy may be needed to maintain improvements in functioning.
- Techniques may involve movement therapy and electrical stimulation of the brain to counter the deficits in motor and/or coginitive functioning that may be experienced following a stroke, for instance
Although it shows that the brain sometimes needs help to “fix itself” completely and successfully, it also shows research has been used to imrpove treatment for people who have suffered trauma to their brain, thereby increasing their chances of disability free recovery.
What is a limitation of plasticty and functional recovery?
Limitation : Coginitive reserve
Another limitation of the brain’s ability to rewire itself is that individual differences could impact recovery rates after trauma.
- Schneider et al. (2014) revealed that the more time people who a brain injury had spent in education the greater their chances of disability free recovery.
- A greater cognitive reserve.
- 40% of people who achieved DFR had 16+ yrs in education.
- 10% of people who had less than 12 yrs.
Implies that people with brain damage who have insufficient cognitive reserve are less likely to achieve full recovery.
What is a strength of using Fmris to investigate the brain?
Strength : Good spatial resolution
- Unlike other scanning techniques such as PET scans, it does not rely on the use of potentially harmful radiation.
- It has very good spatial resolution. This means that it produces images that depict detail by the millimetre, making it possible to get a clear picture of how activity is localised in the brain.
What is a weakness of using Fmris to investigate the brain?
Limitation : Poor temporal resolution
- fMRIs can only measure blood flow, it cannot provide a direct measure of neural activity and so it can be difficult to tell exactly what kind of activity is being shown on the screen. This means it is not a truly quantitative measure of mental activity in these areas of the brain.
- Also means that we cannot infer causation for the changes being observed.
Very poor temporal resolution - time lag of 5seconds
