Localisation

• Localisation of function of the brain

  Specific functions belong to specific areas of brain
• Pre-19th century theory

  • Holistic theory; all parts of brain involved in thought and action
  • Suggests if a part broken, nothing function at all
• Post-19th theory

  • Localisation theory; Broca & Wernicke, specific parts for specific roles
  • Damaged part would only affect damaged function
• Brain hemispheres

  • Left hemisphere controls right body
  • Right hemisphere controls left body
• Lateralisation

  One hemisphere dominates functions
• Grey matter

  Cerebral cortex – outer layer of brain, grey colour
• Broca's area

  • Frontal lobe, left hemisphere, related to speech production
  • Lesions in right hemisphere do not have speech deficit
  • 1861 – patient couldn't say anything but 'Tan'
  • Lesion found in left hemisphere
• Wernicke's area

  • Temporal lobe, comprehension of language
  • Overlaps into motor regions and sensory regions – vocals and process stimuli for meaning
  • Both Broca's and Wernicke's areas work together to create coherent conversation
• Frontal lobe

  • Motor cortex – voluntary movement [send signal to muscles of body]
  • Damage = struggle with coordination and movement control
• Parietal lobe

  • Somatosensory cortex – represents sensory info from skin receptors
  • The amount on a body part denotes sensitivity e.g. face and hands
• Occipital lobe

  Visual cortex – processes visual info
• AO1

  • Localisation vs holistic – post 19th vs pre-19th
  • Hemispheres & cerebral cortex – lateralisation and cerebral cortex, 'grey matter'
  • Motor, somatosensory, visual and auditory centres – frontal, parietal, occipital and temporal lobes
  • Language area of brain – Broca and Wernicke's areas
• AO3 strength - brain scan

  
  

  • Petersen 1988 – Wernicke active listening, Broca active reading; Tulving 1994 –semantic and episodic in PFC
  • Broca for speech production, Wernicke for lang comprehension
  • brain scan as objective measurement of activity, support localisation - sound scientific evidence therefore high validity
• AO3 strength - neurosurgical evidence


  
  

  • Dougherty 2002 – OCD patients successful response to cingulotomy [lesion of cingulate gyrus] post-32 weeks
  • modern procedure reduces compulsive acts due to removing areas influencing it
  • localised symptoms and behaviours associated w/ serious mental disorders
• AO3 limitation - holistic animal studies


  
  

  • Lashley 1950 – rats with a partially removed cortex learn a maze
  • holistic distribution of higher cognitive functions – learning required every part of cortex
  • learning is too complex to be localised and requires involvement of whole brain
• AO3 counter to limitation


  caution needed for drawing conclusions from animal studies and applying to humans – human cortex more developed than animals; therefore, low generalisability
• label centres of the brain

  .

  A) Broca's

  B) motor

  C) visual

  D) frontal

  E) parietal

  F) Wernicke's

  G) occipital

  H) somatosensory

  I) auditory