1. Language & Consciousness
Lecture 27

2. 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 ~

3. 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 ~

4. Mind/Brain Relationship
Monism
mind product of brain function
Dualsim
fundamentally different and separate
Split brain  2 minds?
commissurotomy
Monism?
Dualism? ~

5. 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 ~

6. 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? ~

7. Cat Neuroanatomy CC

8. 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 ~

9. Discrimination Training
Differential training
left: triangle  reward
right: circle  reward
no pressing for non-rewarded shape
Hemispheres learned different things
separate consciousnesses? ~

10. 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 ~

11. Human Split-Brain Research
Discrimination training
same as animals
Verbal identification of objects
visual
tactile
Other interesting phenomenon
L & R competition
and more ~

12. LVF RVF
Speech Mute L R
Body Body

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

14. LVF RVF
Speech L R

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

16. LVF RVF
Speech Mute L R CC

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

18. LVF RVF
Speech L R

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

20. LVF RVF
Speech Mute L R CC

21. 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. ~

22. LVF RVF
Split-brain
Speech Mute L R
Body Body

23. 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.” ~

24. LVF RVF
Speech Mute L R CC

25. 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 ~

26. 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? ~

27. 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 ~