Localisation of function

• What is localisation of function?

  • Theory that different areas of the brain are responsible for different behaviours, processes or activities
  • Also known as cortical specialisation
• What are the cortexes within the brain?

  • Motor
  • Somatosensory
  • Visual
  • Auditory
• What are the 4 lobes within the brain?

  • Frontal lobe
  • Parietal lobe
  • Occipital lobe
  • Temporal lobe
• Describe the motor area

  • Controls voluntary movement in opposite side of the body
  • Located in the back of the frontal lobe
  • Damage may result in loss of control over fine movements
• Describe somatosensory area

  • Receives sensory information from skin (e.g. touch)
  • Located in front of parietal lobe
• Describe visual area

  • Processes visual information from right visual field to left visual cortex and vice versa
  • Located in occipital lobe
  • Damage to either hemisphere can produce blindness in corresponding visual field
• Describe auditory area

  • Analyses speech based information
  • Located in temporal lobe
  • Damage may produce partial hearing loss
• Describe Broca's area

  • Located in frontal lobe in left hemisphere
  • Responsible for speech production
  • Damage to Broca's area causes Broca's aphasia where speech becomes slow, laborious and lacks in fluency
• Describe Wernicke's area

  • Located in temporal lobe in left hemisphere
  • Responsible for language comprehension
  • Damage may result in Wernicke's aphasia where patients produce nonsense words (neologisms)
• What is the outer layer of the brain

  • Cerebral cortex
  • 3mm thick
  • Known as 'grey matter'
• What is the holistic theory which argue against localisation?

  • The idea that all parts of the brain are involved in processing thoughts and action, not specified areas
• Case study support PG (AO3)

  • Phineas Gage, survived a metre-long pole pass through left cheek, eye and skull
  • Damaged frontal lobe effecting his personality and processing
  • Supports localisation as frontal lobe can be linked to mood regulation and higher orders such as decision making (may explain his divorce)
  • Strong real life support
• PG case study extra point (AO3)

  • At the time the brain was thought to work holistically
  • One doctor believed Gage's brain compensated for the damage and concluded it was multi-functional throughout
  • Other argued the area that had been damaged housed the reasoning function of the individual
  • This explanation was correct due to discovering localisation and therefore supports theory
• Lashley's rat study eval point (AO3)

  • Removed cortex of rats 10-50%
  • Assessed ability to learn maze
  • No area was proven to be more important than any other therefore supporting a holistic explanation
  • Therefore, learning is too complex to be localised, every part of the cortex is required to learn effectively
  • Animal study cant be generalised, low EV
• Brain damage as an eval point undermining localisation of function (AO3)

  • Brain is able to reorganise itself after damage to recover the lost function (plasticity and functional recovery)
  • Law of equipotentiality suggests that same neurological action can be achieved regardless of brain areas being affected
  • Undermines importance of localisation
  • E.g. EB operated at 2 1/2 years removing tumour from LH, language abilities disappeared but by 17 could function normally, RH compensated