Relationship between spike-wave discharges and vigilance levels in rats with spontaneous petit mal-like epilepsy

The relationship between states of vigilance and spike and wave discharges (SWD) was examined during 12 hours in 4 Wistar rats from a strain bred for spontaneous generalized non-convulsant seizures. On the basis of cortical and hippocampal EEG and EMG activity, wakefulness (W), slow wave sleep (SWS) and paradoxical sleep (REM) were distinguished. Of the SWD 86% occurred during quiet W, 14% during the first minutes of SWS. No SWD occurred during active wakefulness and they were exceptional during REM. These results show that the states of quiet W and transitional states favour the SWD in rats with petit mal-like epilepsy, as in human petit mal.