Post on 18-Jan-2016
Language &Consciousness
Lesson 26
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 ~
Language & Consciousness Experiment
put one hemisphere asleep• Sodium amytal
Right hemisphere asleep object in right hand (behind back) can verbally ID
Left hemisphere asleep In R. hand no verbal memory In L. hand can ID by touch ~
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
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 ~
Speech Mute
Body Body
L R
LVF RVF
Normal subjectCC intact
LVF RVF
What did you see?
~
Speech
L R
LVF RVF
What did you see?
info to Left via CC ~
Normal subject
LVF RVF
Speech Mute
L RCC
LVF RVF
CC
Split-brainCC cut
LVF RVF
What did you see?
~
Speech
L R
LVF RVF
CC
Split-brain
LVF RVF
What did you see?
~
CCSpeech Mute
L R
LVF RVF
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. by touch ~
Split-brain
Speech Mute
Body Body
L R
LVF RVF
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.”
Like Clive Wearing’s writing His explanation: “unconscious writing”
Simultaneous lateralized inputs? ~
Speech Mute
L RCC
LVF RVF
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? ~
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 ~