Differential effects of colchicine lesions of dentate granule cells on wet dog shakes and seizures elicited by direct hippocampal stimulation.

Direct electrical stimulation of either the dorsal or ventral hippocampal formation elicits wet dog shakes and overt seizures. Destruction of dentate granule cells in the dorsal hippocampal formation does not significantly reduce the number of wet dog shakes elicited by ventral hippocampal stimulation. However, destruction of dentate granule cells in the ventral hippocampus virtually eliminates wet dog shaking elicited by dorsal hippocampal stimulation. Destruction of either dorsal or ventral dentate granule cells lowers the threshold for eliciting forelimb clonus with rearing. These results suggest that dentate granule cells in the ventral hippocampus are essential for wet dog shakes elicited by intrahippocampal stimulation. However, dentate granule cells throughout the hippocampal formation appear to play an important inhibitory role in the spread of seizure activity within the hippocampus.