Cortical slow potential changes during convulsions induced by maximal electroshock or penicillin focus.

We have described the occurrence in freely moving gerbils of slow potential changes (SPC) in two different models of experimental epilepsy: 1) maximal electroshock and 2) bilateral epileptic foci induced by penicillin. SPC is considered a by-product of epileptiform activity in both models and correlates to the SPC which occurs during spreading depression. In the first model there develops a cortical SPC simultaneous with a depression of EEG activity, although there is no propagation of the wave. We suggest that a non-propagated multifocal depression (MD) occurs in the MES model. In the model of focal epilepsy, all requirements are fulfilled, and the SPC is characterized as the one which occurs during spreading depression propagating with an average velocity of 8 mm/min.