5. Functions of Brain

• 1. Localisation of Function in Brain


  Localisation of Function - diff areas of brain responsible for diff behaviours/processes.

  • Paul Broca + Karl Wernicke (19th cent), specific areas of brain associated w/ physical/psychological functions; went against holistic theory.
  • if certain areas brain damaged, then functions associated affected too.
• 2. Localisation of Function in Brain

  Hemispheres of Brain + Cerebral Cortex:

  • brain divided into left hemisphere, right hemisphere; some functions controlled by particular hemisphere = ’lateralisation’.
  • activity on LH side of body controlled by right hemisphere; activity RH side body controlled by left h.
  • outer layer of both hems. = cerebral cortex.
• 3. Localisation of Function in Brain

  Motor, Somatosensory, Visual + Auditory Centres:

  • cortex of both hems. sub-divided into 4 lobes = frontal l, parietal l, occipital l, temporal l.
  • back of frontal lobes = motor area, controls movement in opposite side body; damage = loss control of movements.
  • front of parietal lobes = somatosensory area, where sensory info from skin represented; amount of som. area devoted to body part denotes sensitivity (e.g. receptors for face/hands occupy over 1/2 som. area).
• 3a. Localisation of Function in Brain

  Motor, Somatosensory, Visual + Auditory Centres:

  • occipital lobes = visual area; sends info from right v.f. to left visual cortex (and other way round); damage to left hem = e.g. blindness in right v.f. of both eyes.
  • temporal lobes = auditory area, analyses speech info; damage = hearing loss; damage to Wernicke’s area affect ability comprehend language.
• 4. Localisation of Function in Brain

  Language Area of Brain:

  • language restricted to left side brain.
  • Broca identified area in left frontal lobe responsible for speech production; damage to Broca’s area = Broca aphasia = slow speech, lack fluency.
  • Wernicke, described patients who had difficulty understanding language; Wernicke’s area (left temporal lobe) responsible for lang comprehension; damage = Wernick’s aphasia (nonsense words).
• 5. Localisation of Function in Brain

  Phineas Gage:

  • explosion incident = pole through his left eye, up through most of left frontal lobe.
  • survived but damage affected personality; became quick-tempered/rude.
  • suggests frontal lobe responsible for mood regulating.
• Localisation of Function in Brain (Evaluation)

  Strength:

  P - support for functions being localised, especially in language/memory.

  E - Peterson (1988), brain scans show Wernicke’s area active in listening task + Broca area active in reading task, suggests differing functions.

  E - Tulving (1994), LTM; semantic + episodic memories in diff part of prefrontal cortex.

  L - support = credibility.
• Localisation of Function in Brain (Evaluation)

  Strength:

  P - support from unique case of Phineas Gage, localisation.

  L - real-life app.

  Limitation:

  P - uniqueness = low gen.
• Localisation of Function in Brain (Evaluation)

  Limitation:

  P - Lashley suggests higher cog functions not localised but distributed in holistic way.

  E - removed areas of cortex in rats learning maze; no area proven more important than any other in ability learn maze.

  E - process of learning used every part of cortex.

  L - suggests learning to complex to be localised, uses whole brain.

  Counter-Point:

  P - animal studies = low gen between rat/human brain.