Frontal kindling in rabbits and its influence on visual and auditory evoked response

Frontal kindling in rabbits, prolongation of the duration of afterdischarge concomitant and clinical manifestations and the epileptic foci (primary and independent secondary foci) were revealed. Auditory and visual evoked responses were recorded after completion of the kindling phenomenon. 1. Electrical stimulations, 300 microA, 60 Hz. 1 msec in duration, 2 sec train, were applied once a day. Clinical manifestations were divided into five stages: 1) the arrest of behavior or no response, 2) the adversive movement with a tonic and/or clonic convulsion of left paw, 3) the adversive movement following mastication, facial spasms and postictal stupor, 4) falling down abruptly and generalized convulsive seizure, and 5) generalized seizure followed by rotatory movement, vocalization and myoclonus. The appearance of five generalized convulsions was defined as a completion of the kindling phenomenon. 2. The duration of afterdischarge increased stepwisely from 2--3 sec to more than 400 sec. However, there was no constant duration of AD even though the animal showed generalized convulsion after completion of the kindling phenomenon. 3. Visual and auditory evoked responses were recorded after completion of kindling. There was a change in the auditory evoked response but not in the visual. A shortening of the latency of P2 component (73.3 msec in peak latency), N2 component (146.7 msec in peak latency) and amplification of the amplitude of N2 component were noticed. Thus, the intermittent weak electrical stimulation on the frontal cortex in rabbits induced generalized convulsion and produced primary and independent secondary epileptic focus on EEG, and the change of auditory evoked response was recognized in kindled animals.