Differences of visual evoked potentials (VEPs) evoked by contralateral or ipsilateral monocular and binocular flash stimuli
枝川, 浩二 徳島大学
植村, 桂次 徳島大学
吉松, 誠 徳島大学
大蔵, 雅夫 徳島大学
生田, 琢己 徳島大学
visual evoked potential
monocular vs binocular
contralateral vs ipsilateral
Differences among VEPs evoked by left and right monocular, and binocular flash stimuli were studied with 40 healthy male subjects (21-33 y.o.). VEPs were evoked by LED flash stimuli and derived from the six derivations and recorded with 1024 msec of analysis time. The following results were obtained.
1) In all of six derivations, the contours of the group mean VEPs were roughly similar in both ipsilateral left monocular and contralateral right monocular stimuli. These findings demonstrate that response characteristics and receptive field properties of the two eyes are well coincided with each other.
2) In details, the latencies of the short and middle latency components of the third (O 1→T 5) and the forth derivation (O 1→Cz) in contralateral right monocular VEPs were significantly shorter than those in ipsilateral left monocular VEPs. In all derivations, the peak to peak amplitudes in contralateral right monocular VEPs were significantly larger than those in ipsilateral left monocular VEPs. These findings verified the hemispheric dominant laterality of the contralateral eye, even with latencies, besides with amplitudes.
3) As compared with left monocular VEPs, the latencies of the short and middle latency components in binocular VEPs were significantly short and the peak to peak amplitudes in binocular VEPs were significantly large. These findings might suggest the existence of "binocular depth cells" of the monkey, which respond when the two eyes stimulated simultaneously, even in man.
4) In details, the latencies of the long latency components in binocular and contralateral right monocular VEPs were significantly longer than those in ipsilateral left monocular VEPs. This finding suggests the delay of the alpha regeneration as a photic after discharge following VEPs, because binocular and contralateral right monocular stimuli are stronger than ipsilateral left monocular stimuli.
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