Electrodes were implanted into dorsal hippocampus (CAI), ventral CAI, dorsal dentate gyrus or ventral dentate gyrus. Epileptiform afterdisvharge (AD) thresholds were lower in dorsal areas than in ventral areas. Dorsal areas, however, required a greater number of stimulations to develop (“kindle”) a fully generalized convulsion than did ventral areas. Thresholds and kindling rates in the dentate gyrus were intermediate between dorsal and ventral CAI, except for the ventral dentate which had higher AD thresholds than ventral CAI.
Secondary sites within the hippocampus subsequently kindled within a few stimulations following completion of kindling in the primary site, regardless of which hippocampal area served as the primary site.