Localisation of function in the brain and hemespheric lateralisation: motor, somatosensory, visual auditory and language centres; Broca`s and Wernicke's areas;

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  • Damage to the hippocampus means that a person is unable to store episodic memories
  • the left and right brain hemispheres are bridged by the corpus callosum - a bundle of fibres that acts as a communication pathway so both hempispheres can exchange information
  • Phineas Gage (case study for Localisation of Function) - following an accident with a dynamite blast a metal pole was blown through his chin and the top of his forehead. He recovered quickly but got an infection. While he physically recovered completely with the exception that he was blind in his left eye, he was psychologically changed dramatically - exhibitting unreliable, hostile and rude behaviour never seen before. His doctor (Dr Harlow) beleived that this provided evidence of localisation of function in the brain and the damaged area had housed planning, reasoning and individual control. He was proved to be correct in later research. However, the validity of the behaviour comparison is limited because there is no record of his actions before the accident to ascertain a clear picture of his previous personality
  • Localisation - in terms of the brain, this means the part of the brain in which a function is carried out
  • Contralateral - when the right hemisphere deals with the left side of the body and vice versa
  • Brain is contralateral in most people, so if a person suffered a stroke in the right motor cortex / half of the brain, the left side of thte brain would be impacted
  • what you see in your right peripheral visual field is processed in the left hempisphere
  • Auditory data is gathered from both ears but processing is crossed
  • taste and smell are contralateral (taste on the left side of the tongue and smell in the left nostril are processed by the right hemisphere)
  • division of function between the two hemispheres is known as hemispheric lateralisation
  • Hemispheres are not symmetrical as functions differ

Left Hemisphere:

  • 97% of people contain language processing in this half of the brain
  • therefore, a stroke on the left half of the brain can result in speech and language impediment
  • Broca`s and Wernicke`s area are located here
  • focuses on detail while the right hemisphere looks at overall patterns - the KH study indicated that there is greater left hemisphere activity observing small details of a picture rather than looking at it hollistically

Right Hemisphere:

  • recognises the emotions of others
  • Heller and Levy (1981) - a picture was shown to people with right hemisphere damage which was split in half showing two different emotions. The participants only acknowlegdged / registered the emotion on the left side of the image, providing evidence for the brain being contralateral
  • registers / handes spatial relations (proprioception is the ability to know the position of limbs…

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