Language & Consciousness

1. Language &Consciousness Lesson 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. 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 ~

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

6. 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 ~

7. 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? ~

8. CC Cat Neuroanatomy

9. 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 ~

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

11. 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 ~

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

13. LVF RVF SpeechMute L R BodyBody

14. LVF RVF • What did you see? ~ Normal subject CC intact

15. LVF RVF Speech L R

16. LVF RVF • What did you see? • info to Left via CC ~ Normal subject

17. LVF RVF Speech Mute L R CC

18. LVF RVF • What did you see? ~ Split-brain CC cut CC

19. LVF RVF Speech L R

20. LVF RVF • What did you see? ~ Split-brain CC

21. LVF RVF Speech Mute L R CC

22. 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 ~

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

24. 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? ~

25. LVF RVF Speech Mute L R CC

26. 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 ~

27. 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? ~

28. 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 ~