Localisation of Function in the brain

• Holistic Theory - Idea that all parts of the brain were involved in processing thought and action
• Localisation - Theory that specific areas of the brain are associated with particular physical and psychological functions
• Lateralisation - Dominance of one hemisphere of the brain for particular physical and psychological functions
• Broca's Area:

  • Speech production
  • Damage to area would result in aphasia, inability to produce speech
• Wernicke's Area:

  • Language comprehension
  • Damage to area would result in aphasia, inability to understand speech
• Somatosensory:

  • In parietal lobes
  • Where sensory information from the skin is localised
  • Amount of somatosensory area devoted to particular body part is directly proportional
• Motor Area:

  • In frontal lobes
  • Controls voluntary movement in opposite side of body
  • Damage to area results in loss of fine motor skills
  • Broca's area in left frontal lobe
• Visual Area:

  • In occipital lobe
  • Information is inverted
  • Damage to one side could mean vision loss in opposite eye
• Auditory Area:

  • In temporal lobes
  • Analyses speech based information
  • Damage to area may cause hearing loss
  • Wernicke's area located here
• AO3 - Brain Scan Evidence:


  + MRI scans produce fantastic spatial resolution

  + Provide direct and conclusive evidence for localisation of function

  + Tulving showed that different types of LTM were located in different parts of the prefrontal cortex
• AO3 - Neurosurgical Evidence:


  + Lobotomy - Removal of brain tissue

  + Leucotomy - Cutting the connections to a particular part of the brain

  + Still used today for treatment in severe depressives and extreme cases of OCD

  + Success of these procedures strongly suggests symptoms and behaviours associated with serious mental disorders are localised

  + Direct Support for localisation
• AO3 - Phineas Gage: 


  + Case study evidence

  + Damage sustained to most of his left frontal lobe in a railroad accident at work

  + Changed his personality and mood

  + Demonstrates that certain brain functions area localised
• AO3 - Lashley:


  _ Work of Lashley suggested basic motor and sensory functions were localised but higher mental functions weren't

  _ Through experiments on rats learning to run a maze, found learning was not localised but involved the whole brain

  _ Supporting holistic view of brain function
• AO3 - Impact of Lashley: 


  _ Impact of Lashley's findings, effects of damage to brain would be determined by extent rather than location of damage

  _ View has received much support over last 70 years from discovery that humans are able to regain some of their cognitive abilities following damage to specific areas of the brain

  _ Plasticity shows localisation can be overcome