On the Flash Light Response Activities in the Visual Cortex of Unanesthetized Cats

Single and rhythmic flash light average responses in the visual cortex (lateral gyrus) of immobilized cats by administration of Flaxedil were observed in their time- (Fig. 2C & 3), spatio-temporal- (Fig. 4) and frequency- patterns (Fig. 5B & C). Four positive negative diphasic average deflections were capable of tracing from a variety of portions in the lateral gyrus, each of which was able to designate, for convenience sake, P1, N1, P2, N2, P3, N3, P4 and N4 respectively (Fig. 3) . Their average peak latencies were 21.6, 45.0, 63.4, 78.5, 106.9, 117.3, 154.9 and 178.3 msec respectively, so that P1 and N1 responses were the well-known primary responses. The most conspicuous responses were evoked from the mid lateral gyrus, wherein the early components P1, N1 and P2 due to contralateral stimulus were larger than those evoked by ipsilateral one, but N2 was ipsilaterally dominant. Later components of ipsi- and contralateral responses than N2 were not the same each other in their patterns. Though binocular responses were more prominent than both of ipsi- and contralateral monocular ones, occlusive binocular interaction was revealed in the positive components P1, P2 and P3, whereas facilitatory interaction in the negative components N1, N2 and N3. It was verified in the spatio-temporal average response patterns that primary positive Pi response was unable to observe in the anterior lateral gyrus, but the secondary positive P2 response, which was distinctly and ipsilaterally dominant, was suggested to be an irradiation of P2 in the mid lateral gyrus, in addition, that negative components, N1, N2 and N3 were augmented by binocular stimulation irradiating beyond the extent of responses due to the monocular stimuli to both of anterior and posterior directions