Discharge response of cerebellar Purkinje cells to stimulation of C-fiber in cat saphenous nerve.

Experiments were performed in cats under chloralose anaesthesia and immobilized by Flaxedil. The discharge responses of cerebellar Purkinje cells (PC) were recorded with a microelectrode. The spontaneous activities of PC consisted of simple spike (SS) and complex spike (CS). When the saphenous nerve was stimulated at a low intensity, which elicited the A-fiber input only, the discharge responses (A-CED) consisted of an early component with short latency and late component with long latency in PC-SS and PC-CS. After A-fibers were blocked selectively by the polarizing current, the stimulation at the strength of C-fiber suprathreshold evoked the characteristic responses (C-CED) of PC-SS and PC-CS with middle latency. However, the C-CED could not be evoked by the inputs of A- and C-fibers simultaneously. These results suggested that the pure C-fiber input reaching the cerebellar PC passed through not only climbing fibers, but also mossy fibers, and elicited the characteristic responses (C-CED); these responses were neither the early component nor late component of the A-CED. When A- and C-fiber were activated at the same time, the C-CED might be inhibited by the A-fiber inputs.