P3-3-1. Features of the correlation between the sites of EEG based on the difference in duration of epileptiform discharges

To investigate differences in the duration of epileptiform discharges, wavelet-crosscorrelation analysis was performed to identify correlations and time-lags between sites of the brain. Electroencephalography recordings were categorized into two time spans according to the duration of the epileptiform discharge: short run, 2–3 s; and long run, ⩾3 s. Both runs were subcategorized into before, during, and after epileptiform discharge groups. The EEG was divided into 2-s segments. In all patients, wavelet-crosscorrelation coefficients (WCC) and time-lag (LAG) at 6 Hz were calculated between all electrodes, and between all electrodes and the temporal region electrodes for each segment. In both runs, comparison of all electrodes revealed that the highest correlation occurred during epileptiform discharge. In both runs, comparison of the temporal region electrodes revealed that similar WCC and LAG values occurred before and during epileptiform discharge. In addition, the results of the long run indicated that similar WCC and LAG values occurred after epileptiform discharge, which suggest that the temporal region of the brain remains in a state of preparation for a seizure in cases of long runs, even after epileptiform discharge.