An intracellular study of pudendal afferent inputs onto tail motoneurons in the spinalized cat.

Postsynaptic potentials, elicited by stimulation of the sensory pudendal (SPud) and superficial perineal nerves (SPeri) on both sides, were recorded from motoneurons innervating tail muscles in the non-anaesthetized and spinalized cat. The stimulation of SPud and SPeri on both sides predominantly produced excitatory postsynaptic potentials (EPSPs) in all kinds of tail motoneurons (70-95%). The inhibitory postsynaptic potentials (IPSPs) were often observed in motoneurons innervating ventral tail muscles (30-33%). The means of averaged central latencies of EPSPs and IPSPs ranged from 4.3 to 7.3 ms, and from 4.6 to 8.4 ms, respectively. The findings suggests that polysynaptic neuronal pathways from pudendal nerve to tail motoneurons produce tonic activities of all tail muscles to raise the tail in micturation, defecation and sexual movements which are induced by stimulation of pudendal nerves.