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Lateralization of Function Hemispheres specialized
process information differently L: “analytic” vs R: “holistic” information shared via commissures
Language meaning Left hemisphere emotional content Right hemisphere
Aphasia language impairments ~
Lateralization: Language Evidence from stroke victims Left hemi. damage
aphasias paralysis: right side
Right hemi. damage no aphasias paralysis: left side
Females less lateralization unilateral lesion less aphasia ~
Language: Cortical Localization
Broca’s Area frontal lobe motor programs damage production deficits
Wernicke’s area Temporal lobe meaning of words damage comprehension deficits ~
Wernicke’s Area
comprehension
Broca’s AreaProduction
LeftHemisphere
W
B
Language: Cortical Localization
Language & Consciousness
Declarative memory deficits no conscious memory
Infantile amnesia < 2-3 yrs old
WADA test sodium amytal anesthetize brain hemisphere inject left or right jugular ~
Language & Consciousness
Experiment put one hemisphere asleep place object in left hand (behind back)
Right hemisphere asleep can verbally ID
Left hemisphere asleep no verbal memory of object can ID with left hand ~
Mind/Brain Relationship Monism
mind product of brain function Dualsim
fundamentally different and separate
Split brain 2 minds? commissurotomy Monism? Dualism? ~
Split Brain Research
Commissurotomy sever corpus callosum
Humans treatment of severe epilepsy
Animals also sever optic chiasm only ipsilateral visual inputs
No communication b/n hemispheres ~
Animal Research
Myers & Sperry - Nobel prize 2 consciousnesses in 1 body?
Cats & monkeys cut corpus callosum & optic chiasm
Completely lateralized visual input left eye left hemi only right eye right hemi only
Do hemispheres have different experiences? ~
Discrimination Training Left eye open Discrimination training
triangle press button reward circle press button no reward
After learned cover left eye no longer performs task information not available to right
hemi 1 hemi learned association
other one did not ~
Discrimination Training Differential training
left: triangle reward right: circle reward no pressing for non-rewarded shape
Hemispheres learned different things separate consciousnesses? ~
Human Split-Brain Research Commissurotomy epilepsy tx
optic chiasm intact no apparent deficits contralateral visual inputs
Lateralized visual input Tachistoscope or T-scope < 200 msec info to 1 hemisphere ~
Human Split-Brain Research
Discrimination training same as animals
Verbal identification of objects visual tactile
Other interesting phenomenon L & R competition and more ~
I.D. by R. Hemisphere
L. Hemi no knowledge of key How can R. hemi identify?
reach into bag w/ L. hand I.D. the key
R. hand cannot I.D. ~
Paul - Mr. P.S.
Split-brain patient R. & L. hemi language
spell w/ L. hand using scrabble letters “I know it wasn’t me that did that.” ~
Point to the object best related to what you see R. hand chicken L. hand shovel
“I saw a claw and I picked the chicken, …
and you have to clean out the chicken shed with a shovel. “
Confabulation ~
Paul - Mr. P.S.
Paul - Mr. P.S.
T-scope to ask questions Who is your girlfriend?
R & L same answer Career choice: I want to be a _____.
L. hemi. doctor R. hemi race car driver
2 consciousnesses in 1 body? ~