[The stimulating effects of contralateral glossopharyngeal and hypoglossal afferent fibers on the glossopharyngeo-hypoglossal reflex activities in the frog].
American Bullfrogs, Rana catesbiana, immobilized with suxamethonium chloride (20 mg/kg b. w., i. p.), were used. By stimulating the glossopharyngeal (IX) nerve, reflex activities, composed of early (10-20 ms in latency) and late (greater than 20 ms) components, were evoked in both protoractor branch (P. br.) and retractor branch (R. br.) of the ipsilateral hypoglossal (XII) nerve. Contralateral IXth nerve stimulation increased the reflex activities of both components in the P. br. elicited ipsilaterally by the homonymous nerve. Whereas, it increased the reflex activities of the early component in the R. br. but, decreased that of the late component. On the other hand, stimulation of P. br. in the contralateral XIIth nerve increased the activities of both components in the P. br. and those of the late component in the R. br., but did not affect the activities of the early component in the R. br. The time course of these effects was similar to that by contralateral IXth nerve stimulation. The present findings strongly suggest the existence of afferent fibers in the XIIth nerve.