[Basic studies on the photically evoked lid potential changes in rabbit, with special reference to orbicularis oculi reflex].

In order to elucidate the origins of the potential changes in the eyelid elicited by flash stimulation in rabbits, their physiological properties were studied under various conditions. In the present study, they were specially discussed from the standpoint of orbicularis oculi reflex. The photically evoked lid potential changes were obtained with the summation technique by the signal processor (7 T 08, SAN-EI, Tokyo). In addition, the average summated responses of photically evoked lid MV responses, electroretinogram (ERG) and the electroencephalogram (EEG) were recorded simultaneously under dark-adapted conditions and studied polygraphically. The results obtained were as follows: The average photically evoked lid potential changes in rabbits were shown to be composed of early rapid and slow components and late slow component. The early rapid and slow components corresponded to dominant vibrations of the evoked lid MV responses and the a and b waves with oscillatory potential of the ERG. The early rapid components, which corresponded to dominant vibrations of the evoked lid MV responses, consist of positive, negative and positive components with peak latencies of 24.8 +/- 2.7, 29.4 +/- 3.7 and 33.1 +/- 2.5 msec, respectively. In the average lid potential changes led off bipolarly from medial and middle parts of the superior lid, the electromyographic components appeared corresponding to the evoked lid MV responses, although the electroretinographic components and late slow component were observed to decreased considerably in amplitude or disappeared almost completely, as compared with those obtained by monopolar leads. In the average lid potential changes obtained by flash stimulation to a single eye, the electroretinographic and electromyographic components disappeared almost completely in the occluded side.(ABSTRACT TRUNCATED AT 250 WORDS)