Hemispheric Specialization and Interhemispheric Interaction in Humans

Eran Zaidel & Jonas Kaplan

Department of Psychology, UCLA

Abstract This course will cover hemispheric specialization and interhemispheric interaction from convergent anatomical, physiological and behavioral perspectives, with a focus on the representation and processing of natural language. We will approach the topic from the joint perspectives of the hemisphere-damaged brain, the split brain, and the normal brain. We will argue that the two cerebral hemispheres provide a model system for how different modules of the mind/brain maintain independence sometimes but interact at other times.

General reading:

Zaidel, E., (2001). Brain Asymmetry. In N. J. Smelser & P. B. Baltes (Series Eds.) & R. F. Thompson (Volume Ed.), International Encyclopedia of the Social & Behavioral Sciences: Vol. 2. Behavioral and Cognitive Neuroscience (pp. 1321-1329). Elsevier: Amsterdam; New York.

Lecture 1: The normal brain

1. Anatomy of the corpus callosum

2. Lateralized lexical decision

3. Behavior vs. imaging

4. Applications: individual differences, Schizophrenia

Required readings:

Aboitiz, F., Scheibel, A. B., Fisher, R. S., & Zaidel, E. (1992). Fiber composition of the human corpus callosum. Brain Research, 598, 143-153.

Iacoboni, M. & Zaidel, E. (1996). Hemispheric independence in word recognition: Evidence from unilateral and bilateral presentations. Brain and Language, 53, 121-140.

Lecture 2: The split brain

1. Disconnection syndrome

2. Right hemisphere language

3. Explicit and implicit interhemispheric transfer

Required reading:

Zaidel, E., Zaidel, D. W., & Bogen, J. E. (1999). The split brain. In G. Adelman & B. Smith (Eds.). Encyclopedia of Neuroscience, 2nd Ed (pp. 1930-1936) (also on CD-ROM). Amsterdam: Elsevier.

Zaidel, E. (1999). Language in the disconnected right hemisphere. In G. Adelman & B. Smith (Eds.). Encyclopedia of Neuroscience, 2nd Ed (pp. 1930-1936) (also on CD-ROM). Amsterdam: Elsevier.

Optional:

Zaidel, E., Iacoboni, M., Zaidel, D. W., & Bogen, J. (in press). The callosal syndromes. In K.M. Heilman & E. Valenstein, E. (Eds.) Clinical Neuropsychology, 4th Edition. New York: Oxford University Press.

Lecture 3: The damaged left hemisphere

1. Modularity

2. Aphasia

3. Alexia

Required readings:

Alexander, M. P. (2000). Aphasia I: Clinical and anatomic issues. In M. J. Farah & T. E. Feinberg (Eds.). Patient-Based Approaches to Cogntive Neuroscience (pp. 165-181). Cambridge, MA: MIT Press.

Luzzatti, C. (in press). Optic aphasia and pure alexia: Contribution of callosal disconnection syndromes to the study of lexical and semantic representation in the right hemisphere. In Zaidel, E. & Iacoboni, M., Eds. (in press). The Parallel Brain: The Cognitive Neuroscience of the Corpus Callosum. Cambridge: MIT Press.

Lecture 4: The damaged right hemisphere

1. Neglect

2. Anosognosia

3. Visuospatial disorders (Balint’s syndrome)

Required readings:

Bisiach, E. (1996). Unilateral neglect and the structure of space representation. Current Directions in Psychological Science 5, 2: 62-65.

Heilman, K. (1991). Anosognosia: Possible neuropsychological mechanisms. In Awareness of Deficit After Brain Injury, G. Prigatano and D. Schacter, eds. Oxford University Press: New York. Pp. 53-62.

Lecture 5: Two hemispheres, one self

1. Self-awareness and brain damage

2. Self-recognition

3. Self-monitoring and feedback

4. Executive functions in the hemispheres

Required readings:

Kaplan, J. & Zaidel, E. (2001). Error monitoring in the hemispheres: The effect of feedback on lateralized lexical decision. Cognition, 82, 157-178.

Keenan, J. P., Wheeler, M.A., Gallup, G., and Pascual-Leone, A. (2000). Self-recognition and the right prefrontal cortex. Trends in Cognitive Sciences, 4, 338-344.