A03 - Localisation of Brain function

• Evaluationof Localisation of brain function - A03 points?

  +support from neurosurgery

  +Brain scan evidence

  +Case study evidence

  -Localisation model has been questioned

  -Research against
• Strength of Localisation of brain function - support from neurosurgery - PART 1


  P: One strength of localisation theory is support from neurosurgery. Neurosurgery adds to the case for brain localisation (but it's rarely used today coz brutality of procedure).

  E: Neurosurgery used to treat mental disorders e.g. cingulotomy involves isolating the cingulate gyrus - dysfunction of this area may be a cause of OCD.
• Strength of LoBF - support from neurosurgery - PART 2

  E: Dougherty et al (2002) studied 44 suffers of OCD who had a cingulotomy. This is neurosurgical procedure involving lesioning of the cingulate gyrus (OCD localised to).  

  At post surgical follow-up after 32 weeks, 30% met criteria for successful response to surgery & 14% for partial response. Almost ½ experienced full/partial recovery.

  L: The success of such procedures strongly suggests that behaviours associated with serious mental disorders are localised (as removal of small parts of the brain aids recovery from these disorders).
• Weakness of LoBF - research against - PART 1


  P: Not all researchers accept brain functioning localised

  E: Lashley (1950) removed different areas of the cortex of rats (up to 50%) who were learning a maze; he found learning inhibited in the same way in all rats, regardless of which area/how much of cortex removed.
• Weakness of LoBF - research against - PART 2


  E: Suggests the processes involved in high cognitive functioning e.g. learning, are distributed more holistically and are not localised since learning requires all of the cortex rather than being confined to a particular area.

  L: Shows that some processes are too complex to be localised to a single area. Showing not all researchers accept that brain functioning is localised.
• Strength of LoBF - Brain scan evidence - PART 1

  P: Another strength of localisation theory is brain scan evidence to support it.

  E: Petersen et al (1988) used brain scans to demonstrate how Wernikes area was active during a listening task and Broca’s active during reading task - suggesting these areas of the brain have different functions.
• Strength of LoBF - Brain scan evidence - PART 2

  E: Also, a study of long-term memory by Tulving et al (1994) revealed semantic and episodic memories are located in different areas of the prefrontal cortex.

  L: Both studies clearly show how different tasks are carried out in physically different areas of the brain, strengthening the case for localisation rather than holism. There now exists a number of sophisticated and objective methods for measuring activity in the brain, providing sound scientific evidence of localisation of function.
• Weakness of LoBF - Localisation model has been questioned - PART 1


  P: One limitation is the language localisation model has been questioned. Despite evidence from case studies to support the function of the Broca’s area and Wernicke’s area, more recent research has provided contradictory evidence. 

  E: Dick & Tremblay (2016) found that very few researchers still believe language is only in Broca’s and Wernicke’s area. Advanced techniques (e.g. fMRI) have identified regions in the right hemisphere and the thalamus.
• Weakness of LoBF - Localisation model has been questioned - PART 2

  E: Dronker’s (2007) et al 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 found evidence to suggest other areas may contributed to failure in speech production.

  E: Results suggest that Broca’s area may not be only region responsible for speech production & deficits found in patients with Broca’s Aphasia could be result of damage to other neighbouring regions.
• Weakness of LoBF - Localisation model has been questioned - PART 3


  L: These results challenge the suggestion that Broca’s area is the only region responsible for speech production. This suggests that, rather than being confined to a couple of key areas, language may be organised more holistically in the brain, which contradicts localisation theory.
• Strength of LoBF - Case study evidence

  P: Case Study Evidence

  E: Unique cases of neurological damage support localisation theory, e.g. Phineas Gage who lost some of his brain in an explosion and his personality changed.

  E: However, it is difficult to make meaningful generalisations baked on a single individual and conclusions may depend on the subjective interpretation of the researcher.

  L: This suggests that some evidence supporting localisation may lack validity, oversimplifying brain processes and undermining the theory.
• Evaluation of Localisation of Brain Function - A03s

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