Language & Consciousness Lecture 27

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 ~

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 ~

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? ~

Cat Neuroanatomy CC

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 ~

LVF RVF Speech Mute L R Body Body

LVF RVF Normal subject CC intact What did you see? an apple ~

LVF RVF Speech L R

LVF RVF Normal subject What did you see? a cow info to Left via CC ~

LVF RVF Speech Mute L R CC

LVF RVF Split-brain CC cut CC What did you see? a cup ~

LVF RVF Speech L R

LVF RVF Split-brain What did you see? Nothing Why not? ~ CC

LVF RVF Speech Mute L R CC

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. ~

LVF RVF Split-brain Speech Mute L R Body Body

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.” ~

LVF RVF Speech Mute L R CC

Paul - Mr. P.S. 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. 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? ~

The Nature of Consciousness Split-brain  split consciousness? Monism vs. Dualism How do you split a nonphysical entity? supports monist view Brain & Behavior mental states  physiological states ~