Forebrain bisection and feline amygdaloid kindling.

Callosal (CC) bisection following completion of primary site amygdaloid kindling modified the established generalized electroclinical seizures into lateralized and asymmetrical ones. Secondary site amygdaloid kindling following the bisection showed not only a lack of transhemispheric positive transfer effect but also a significant interference effect which became maximal with complete CC bisection. It is postulated that the transhemispheric positive transfer effect is primary site hemisphere dependent and is mediated via the cropus callosum, whereas the transhemispheric interference effect is secondary site hemisphere dependent and is mediated via the extracallosal route, probably the brainstem. Our findings suggest that the dynamic functional integrity of the corpus callosum, particularly its anterior to midportion, plays a major role in the mechanisms of generalized convulsive seizure of amygdaloid origin by readily enabling either ictal participation of the secondary site hemisphere during primary site kindling or ictal accession of the primary site kindled mechanisms from the contralateral hemisphere during secondary site kindling.