ao3

• One strength of localisation theory is evidence from neurosurgery

  • damage to areas of the brain has been linked to mental disorders
  • neurosurgery (surgery on the brain) is a last resort method for treating some mental disorders, targeting specific areas of the brain which may be involved
• (+) evidence from neurosurgery

  • e.g. cingulotomy involves isolating a region called the cingulate gyrus which has been implicated in OCD
  • Darin Dougherty et al. (2002) reported on 44 people with OCD who had undergone a cingulotomy
  • At post-surgical follow-up after 32 weeks, about 30% had met the criteria for successful response to the surgery and 14% for partial response
  • The success of these procedures suggests that behaviours associated with serious mental disorders may be localised
• (+) Evidence from brain scans

  • Petersen et al. (1988) used brain scans to demonstrate how Wernicke's area was active during a listening task
  • Broca's area was active during a reading task
• (+) Evidence from brain scans

  • a review of long-term memory studies by Buckner and Petersen (1996) revealed that semantic and episodic memories reside in different parts of the prefrontal cortex
  • These studies confirm localised areas for everyday behaviours
  • Therefore objective methods for measuring brain activity have provided sound scientific evidence that many brain functions are localised
• (-) Counterpoint to evidence from brain scans

  • Lashley (1950) removed areas of the cortex (between 10% and 50%) in rats that were learning the route through a maze
  • No area was proven to be more important than any other area in terms of the rats' ability to learn the route
  • The process of learning seemed to require every part of the cortex rather than being confined to a particular area
  • This suggests that higher cognitive processes, such as learning, are not localised but distributed in a more holistic way in the brain
• (-) Language localisation questioned

  • One limitation is that language may not be localised just to Broca's and Wernicke's areas
  • Dick and Tremblay (2016) found that only 2% of modern researchers think that language in the brain is completely controlled by Broca's and Wernicke's areas
  • Advances in brain imaging techniques, such as fMRI, mean that neural processes in the brain can be studied with more clarity than ever before
  • This suggests that, rather than being confined to a couple of key areas, language may be distributed more holistically in the brain, which contradicts localisation theory
• (+) Case study evidence

  • Unique cases of neurological damage support localisation theory, such as the case of Phineas Gage
  • Gage had damage to left frontal lobe after an accident at work
  • the damage to his brain had left a mark on his personality - by all accounts he had turned from someone who was calm and reserved to someone who was quick-tempered, rude
  • the change in his temperament following the accident suggested that the frontal lobe may be responsible for regulating mood
• (-) However, there are problems with case studies. It is difficult to make meaningful generalisations from the findings of a single individual. Also, conclusions drawn may depend on the subjective interpretation of the researcher.