Facilitation of secondary-site amygdaloid kindling following bisection of the corpus callosum and hippocampal commissure in rats.

Abstract The effects of forebrain bisection on the development of secondary-site amygdaloid kindling in rats were examined. Bisection of the corpus callosum and hippocampal commissure after primary-site kindling had a facilitative effect on the subsequent rate of secondary-site kindling. Although the rate of secondary-site kindling was significantly facilitated after forebrain bisection, bisected rats failed to develop typical bisymmetrical seizures. The bisected rats instead displayed asymmetrical, and in many cases hemiconvulsive, clinical manifestations. Seizure duration and afterdischarge duration were not affected by the forebrain bisection. These data suggest that seizure duration, afterdischarge duration, and the morphology of the seizure are independent aspects of the kindling phenomenon. Furthermore, because the facilitation of secondary-site kindling could not be adequately explained by denervation supersensitivity, we conclude that the callosal and commissural pathways are capable of mediating an interhemispheric interaction that is in turn able to interfere with the rate of seizure development in the intact rat.