EXTRACALLOSAL DELAYED RESPONSES TO CORTICAL STIMULATION IN CHLORALOSED CAT

Abstract

In-terhemispheric linkages via the corpus callosum have been studied anatomically and electrophysiologically and some specific functions of this system have been demonstrated behaviorally. However, since section of the corpus callosum results in remarkably little disturbance of an animal''s behavior, it is reasonable to postulate extracallosal interhemispheric pathways. The experiments of Doty and Rutledge suggest the existence of such pathways, since generalization of conditioned responses between the hemispheres occurs in preparations with the corpus callosum transected when conditional stimuli are applied directly to the cerebral cortex. Since it has been observed that chloralose enhances the responsiveness of the nervous system, animals given this drug were studied to determine if extracallosal inter-hemispheric connections would be disclosed. Under chloralose a late wave was seen to follow a transcallosal response. This late wave has been investigated by means of cortical stimulation and recording procedures, with the transcallosal response serving as a baseline of electrophysiological interhemispheric activity. These investigations were designed to define the characteristics of the late wave.