SPECIFIC AND NONSPECIFIC ACTIVITIES OF THE VISUAL SYSTEM IN RABBITS

The activity patterns (response amplitude-frequency diagram) of ten anesthetized and eleven unanesthetized rabbits brain evoked by repetitive flash stimulation of varying frequencies (1-15/sec) were observed with respect to the stimulating frequency in the lateral geniculate body (GL), optic radiation* (OR), midbrain reticular formation (RF), Pulvinar*(Pul), superior colliculus (CS) and visual (Vc) and limbic cortex* (Lc), wherein those in the starred sites were observed under unanesthetized situation only. The activities in each of the specific and nonspecific structures presented characteristic patterns and in Lc, too. In GL and OR, the initial potential with short duration (A potential) was augmented at 4.5-6/sec flash stimulation and the slow component (C potential) was enhanced at 2-3.5/sec which suggests cyclic activity changes at these frequencies. On the contrary, it was demonstrated that the activities of RF were characterized by 1 and 4/sec under anesthetized state and by vast augmentation at less than 5/sec under unanesthetized state, though no conspicuous cyclic property. In the Lc, an independent cyclic property from the above specific systems was observed. These observations were confirmed by the repetitive electrical stimulation to GL or RF, suggesting that the augmenting and recruiting-like responses play a rôle at least in part. The activity patterns associated mainly with the specific activity were not affected by anesthetic condition, while the activities or the potential components related closely with RF were most affected by anesthesia.