Clusters of spike-wave activity in the eeg in a long term eeg study

Long-term studies in WAG/Rij rats revealed non-random order of appearance of spike-wave activity in EEG. The autocorrelation functions, calculated for sequences of spike-wave discharges (SWDs), revealed the existence of internal correlation which cause grouping of SWDs in the minute range. The time of autocorrelation (AC-? time) was significantly higher during the dark periods then during the light ones. AC-? time correlated positively with the propensity of the spike-wave activity; i.e. aggravation of absence epilepsy lead to less random pattern of SWDs' distribution. This correlation was stronger during the light periods, then during the dark ones. No significant effect of any particular day of the estrous cycle was found. It can be concluded that the appearance of SWD is not random in time but that clusters of SWD appear with a time period in the minute range