Interhemispheric Communication Through the Corpus Callosum

The early brain anatomists assumed highly important functions for the corpus callosum in relating and coordinating the activities of the two cerebral hemispheres. Likewise, the early clinical neurologists believed that destruction of this largest of all fiber tracts in the brain would result in serious functional defects, even in a general intellectual deterioration. However, actual observations on the effect of complete surgical section or of total agenesis of the corpus callosum in man and other animals have indicated a surprising absence of deficit.1-6,8,9This wide discrepancy between the expected and the actual effects of callosal damage has remained one of the enigmas of brain function. Recent investigations of contralateral transfer of training in callosum-intact and callosum-sectioned animals, however, begin to reveal a definite role for the corpus callosum in the realm of "psychic" function. In the cat with the crossed retinal fibers divided at the optic chiasm, visual discriminations