Effects of post-ictal depression on experimental spike and wave discharges.

The effects of post-ictal depression on spike and wave (SW) discharges of feline generalized penicillin epilepsy (FGPE) were studied. After tonic-clonic seizures which are not uncommon in FGPE spindle bursts appeared during the post-ictal period. Upon recovery spontaneous and thalamically evoked SW discharges reappeared. Spindles before penicillin and during post-ictal depression showed a similar intraburst frequency (twice that of SW discharges) in the same animal. These findings add further evidence to the notion that any depression of cortical excitability in FGPE leads to replacement of SW by spindles and thus supports the hypothesis that SW discharges occur in hyperexcitable cortex in response to normally spindle-inducing thalamocortical volleys.