Localisation of Function

• Franz Gall (1758-1828)

  • pioneered the concept of localised functions
  • introduced the idea of phrenology
  • quickly discredited
• Wilder Penfield (1891-1976)

  • discovered that electrical stimulation of the brain produced different responses, including movements and recall of memories, depending on location
  • effectively mapped body parts onto the brain
• Motor Cortex

  • region of the frontal lobe involved in regulating voluntary movement
  • placed at the back of the frontal lobe
  • both hemispheres have on and they control the muscles on the opposite sides of the body
  • there are specialised areas which control different parts of the body
• Somatosensory Cortex

  • at the front or the parietal lobe that processes sensory information such as touch
  • both hemispheres have one and they process touch, pain, pressure, heat from the other side of the body
  • produces the sensation in the relevant location
• Visual Cortex

  • a part of the occipital lobe that receives and processes visual information
  • both hemispheres have one, each receiving input from the opposite side of the visual field
  • different parts are specialised for colour, shape, movement, patterns, recognition, faces etc
  • information is sent on to the other relevant regions necessary
• Auditory area

  • located in the temporal lobe and concerned with the analysis of speech-based information
  • most of the decoding is done before it reaches, so this region is involved in sound recognition, and there are separate sections dealing with music and speech sounds
  • the auditory cortex will send signals on to other brain regions so that an appropriate response can occur
• Broca's area

  • an area of the frontal lobe of the brain in the left hemisphere responsible for language productions
  • using postmortems, Broca studied patients with posterior left frontal lobe damage, they had problems producing spoken and written language
  • Broca's aphasia is a condition characterised by very limited and clumsy speech and writing
• Wernicke's areas

  • an area of the temporal lobe in the left hemisphere responsible for language comprehension and is connected to Broca's area and sensory regions
  • Wernicke's aphasia is a condition characterised by very limited understanding of language and inability to form coherent speech
• Phineas Gage

  • a tamper during the construction of US railroads
  • one day, explosives ignited in the rock and rod was propelled through his skull and survived
  • Harlow, who treated him, wrote on his recovery and life afterwards
  • Gage was impulsive, rude and incapable of reason
  • Gage lost his friends and alienated those who were close to him, they said he was no longer Gage
  • the frontal lobes are responsible for personality and reasoning
• Evaluation

  • Equipotentiality is the idea that basic motor and sensory functions were localised but that higher mental functions were not (plasticity) - Lashley
  • Dejerine found that the loss of ability to read resulted from the damage to the connection between the visual cortex and Wernicke's area
  • Baveiler et al found a large variability in individual patterns of activation across different individuals.
  • Dronkers et al found that from and MRI from preserved brains of Broca's patients, other areas are also responsible for speech production