Responses of cerebellar cortex to electrical stimulation of the glossopharyngeal nerve in the frog.

In the frog cerebellar cortex, electrical stimulation of the glossopharyngeal (IXth) nerve induced negative field potentials with a peak latency of 57 ms whose distribution was bilateral with ipsilateral predominance. The site where the maximum negativity was induced by IXth nerve stimulation was histologically located within the molecular layer near the Purkinje cell layer. In extracellular recording, electrical stimulation of the IXth nerve induced complex and/or simple spike discharges of Purkinje cells. Such evoked potentials and unitary spikes in the cerebellum were attributed to the excitation of the IXth nerve afferents of higher threshold which are mainly composed of fibers sensitive to taste stimulation. These results suggest that gustatory information projects to the cerebellum, as well as those of other kinds of senses, such as touch, visual and auditory sensation.