The role of interhemispheric pathways in generalization of kindled seizures in cats and subhuman primates

The role of interhemispheric pathways in generalization of partial seizures was evaluated in the kindling model of epilepsy. The generalized seizure kindled from the amygdala was asymmetrical in cats with callosal bisection, destruction of massa intermedia of the thalamus or bilateral ventral hippocampus. The generalized convulsion of amygdala kindled cats became asymmetrical or changed into partial seizures by callosal bisection. The fully-kindled amygdala seizure of a split-brain epileptic baboon and rhesus monkey was a hemiconvulsion or an asymmetrical generalized convulsion. The amygdala-kindled bisymmetrical generalized convulsion of the epileptic baboon was changed into a hemiconvulsion or an asymmetrical generalized convulsion. These results indicate that the corpus callosum plays an important, although not exclusive, role in bilateralization of epileptic activity, and its role becomes more important when the animal ascends the phylogenetic scale.