The Split Brain

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The Split Brain Powered By Docstoc
					Split Brains and Consciousness
   Picturing the Hemispheres
• MRI scan of brain,
  image from a virtual
  slice across the top
  of the head
• Convolutions and
  the longitudinal
  fissure separating
  hemispheres are
  visible
               Left Hemisphere


Longitudinal
fissure


                Right Hemisphere
         Brain Organization
• Hemispheric Lateralization
  – cross-over control
           » right brain => left side
           » left brain => right side
  – cross-over visual field
           » right brain => left visual field
           » left brain => right visual field
  – lateralization of function
           » language areas on left, in most people
        History of “Split Brain”
• Roger Sperry (1913-1994)
   – winner of Nobel Prize in
     Medicine, 1981
   – studied nerve
     regeneration in
     amphibians
   – studied effects of split
     brain in mammals
   – used “split brain” to treat
     epilepsy
            “Split” Brains
• Hemispheric Co-ordination
  – Corpus Callosum
  – Movement
    • Eye movement
    • Head/body movement
• Disconnecting the Hemispheres
  – Treatment for Epilepsy
  – Commissurotomy
        Brain Lateralization
• Visual lateralization
  – visual field, not eyes, are lateralized
• Temporal hemi-retina is ipsilateral
• Nasal hemi-retina is contralateral
• Displays and Fixation Points
  Testing Split Brain Patients
• Normal responses under normal
  conditions
• Unusual responses under laboratory
  controlled conditions
  – no naming for displays flashed on the left
  – correct manual search for displays flashed
    on the left
 Understanding in the Split Brain
• Language
  production, right-
  side motor control is
  in left hemisphere

• Left-side motor
  control is in right
  hemisphere

				
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posted:4/26/2011
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