[Effect of diazepam on cyclic changes in excitability in cortical epileptic foci].

Penicillin application to the rat motor cortex and electrical stimulation of n. ventroposterolateralis thalami (VPL) at 1/s frequency and intensity 3 times exceeding a threshold for the primary evoked potential produced an alternation of "active" and "passive" periods--cyclic spike driving. During "active" periods epileptiform discharges appeared regularly at every electric stimulus. During "passive" periods electrical stimulation of VPL resulted in the emergence of evoked potentials only. Injection of diazepam (2 mg/kg) abolished rhythmogenesis in the epileptogenic focus, while 0.1 mg/kg diazepam led to disappearance of cyclic spike driving in the focus. Electrical stimulation of VPL at 2/s frequency restored cyclic spike driving.