Electrophysiological abnormalities in chronic epileptogenic foci: an intracellular study

Intracellular recordings were performed from chronic cobalt epileptogenic foci in rats. Two main features were found: (a) in 29% of the neurons, depolarizations of long duration occurred coinciding with cortical surface paroxysms; and (b) in 13% of the neurons, partial spikes, whose amplitude varied little with membrane DC potential changes, occurred. It is suggested that these phenomena have a dendritic origin, and possible mechanisms underlying the generation of paroxysmal events are discussed.