SEPARATION OF DIFFERENT INTERICTAL DISCHARGE PATTERNS IN ACUTE EXPERIMENTALLY-INDUCED EPILEPTIC FOCI OF THE RAT IN-VIVO

Epileptic discharge patterns in an acute experimental model of epileps y were analyzed. Epileptic foci were induced by epicortical applicatio n of penicillin on the rat motor cortex in vivo. Patterns with regular I/s1 discharges, patterns with irregular discharges of about 0.5/s1 a s well as compound patterns comprising discharges with intervals of ab out 300 ms could be differentiated by means of interval histograms and autocorrelation functions. These patterns occurred in an ordered sequ ence indicating that the different rhythms are activated by a progress ive enlargement of the focus and duration of focal activity. The exper iments suggest that different interictal discharge patterns can occur within the same brain regions and are not specific for a certain etiol ogy; instead they seem to represent 'resonance' frequencies characteri stic for the brain tissue which are disclosed under pathophysiological conditions.