AQA Psychology for A Level Year 2: Rev Guide

Localisation of function in the brain AO3 Evaluation One strength of localisation theory is there is brain scan evidence to support it. Peterson et al. (1988) 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, a study of long- term memory by Tulving et al . (1994) revealed semantic and episodic memories are located in different parts of the frontal cortex. There now exists a number of sophisticated and objective methods for measuring activity in the brain, providing sound scientific evidence of localisation of function. Another strength of localisation theory is support from neurological evidence. Surgically removing or destroying areas of the brain to control aspects of behaviour was developed in the 1950s by Walter Freeman – though these early attempts were brutal and imprecise. Dougherty et al. (2002) reported on 44 OCD patients who had had a cingulotomy (lesioning the cingulate gyrus). At a 32-week follow-up, one- third met the criteria for successful response to surgery and 14 per cent for partial response. The success of such procedures strongly suggests that symptoms and behaviours associated with serious mental disorders are localised. A further strength of localisation theory is support from case studies . Unique cases of neurological damage support localisation theory, such as the case of Phineas Gage who received serious brain damage in an accident. Gage survived but the damage to his brain affected his personality – he went from someone who was calm and reserved to someone quick-tempered, rude and ‘no longer Gage’. The change in Gage’s temperament following the accident suggests the frontal lobe may be responsible for regulating mood. A limitation of localisation theory is the existence of contradictory research. The work of Lashley (1950) suggests higher cognitive functions (e.g. learning processes) are not localised but distributed in a more holistic way in the brain. Lashley 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. As learning required every part of the cortex rather than just particular areas, this suggests learning is too complex to be localised and involves the whole of the brain. Another limitation is that neural plasticity is a challenge to localisation theory. When the brain has become damaged (e.g. through illness or accident) and a 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 – what happens is that other areas of the brain ‘chip in’ so the same neurological action can be achieved. Although this does not happen every time, there are several documented case studies of stroke victims recovering abilities seemingly lost as a result of the illness. Phineas Gage was working on a railroad when a tamping iron shot through his cheek taking a chunk of his frontal lobe with it. Now we’ve all had some bad days, but that takes the biscuit. 1. Select three specific areas of the brain that you have studied and briefly outline the functions of each. (2 marks + 2 marks + 2 marks) 2. Outline research into localisation of function in the brain. (6 marks) 3. Discuss two criticisms of research into localisation of function in the brain. (3 marks + 3 marks) 4. A clinical psychologist’s report on a patient who suffered a brain injury concludes that the patient had damage to the motor, somatosensory and language centres of her brain. Discuss localisation of function in the brain. Refer to the three brain areas mentioned in the psychologist’s report. (16 marks) Knowledge Check 31