抄録
Since Chang (1) demonstrated a potentiation of cortical responses to thalamic stimulation induced by continuous illumination of the retina, many investigations have been performed to elucidate the afferent tonic inhibitory effect on the central visual pathway. Arduini and Hirao (2) have shown that visually evoked responses were influenced directly by spontaneous retinal discharges. These findings have been confirmed with the following studies (3-6) which have postulated tonic suppression on the lateral geniculate neurons by means of recurrent inhibition of the geniculate relay neurons. On the other hand, other investigators (7-9) have demonstrated inhibitory effects on the geniculate neurons derived from the visual cortex. Inhibitory or facilitatory influence on the visual pathway from various brain structures, especially from the brain stem reticular formation, has also been observed by many researchers (10-15).
In previous papers (16, 17), we reported the role of reticular modulation of the visual system by observing the relation of altered visually evoked responses to associated reticular activity with some central depressants. The present experiments were designed to investigate the effects of pentobarbital on such intricate afferent transmissions through the central visual pathway and further to solve the feed back mechanism in the central nervous system.
