Vision in Split Brain - Introduction

Tutorial 11: Vision in Split Brain

Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test

For some people epilepsy is so serious that seizures cannot be controlled with medication. In such instances the fiber tract that connects the two cerebral hemispheres (the corpus callosum) may be severed surgically to reduce the severity of symptoms. The rationale for cutting the corpus callosum in such people is that seizure activity is prevented from spreading. This procedure was successful in reducing seizures, and at first appeared to spare other function. Over time, however, a subtle "disconnection" syndrome emerged from the examination of "split-brain" patients. Extensive study of this syndrome has yielded knowledge of how each hemisphere is unique.

Figure 11 describes the classic experiment used to study split-brain function, and summarizes what we have learned about the cerebral hemispheres from this experimental paradigm. To understand how the split-brain experiment works it is essential to know that each hemisphere receives information primarily from the opposite side of the body and external world. Such is the case for the visual system. In addition, each hemisphere controls body movements on the opposite side.

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Roger Sperry (1913) conducted the first split-brain experiments in the late 60's and early 70's at the California Institute of Technology in Pasadena. Sperry believed in the localization or specialization of function in the nervous system; spending the earlier part of his career studying the effects of disconnecting the cerebral hemispheres of cats on visual function. When the commissurotomy procedure (cutting of the corpus callosum) was initiated for the treatment of intractable epilepsy, Sperry saw an opportunity to increase our knowledge of localized brain function.

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Tutorial 11: Vision in Split Brain

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