[Postsynaptic potentials of motor neurons of neck muscles in the cat evoked by stimulation of the horizontal semicircular canals].

PSPs, evoked by stimulation of the ipsi- and contralateral horizontal semicircular canals (HSC) in motoneurons of neck muscles, were studied in acute experiments on cats under chloralose-nembutal anesthesia. Ipsilateral stimulation evoked EPSP with latencies ranging from 1.8 to 10.0 ms in 25 motoneurons and IPSP with latencies 1.9-3.9 ms in 10 motoneurons. Calculation of conduction time from ipsilateral canal via Deiters nucleus to neck motoneurons gives reason to consider EPSP with latencies less than 3.8 ms as disynaptic, and those with greater latencies as polysynaptic. Contralateral stimulation evoked EPSP with latencies 1.8-6.0 ms in 19 motoneurons and IPSP with latencies 3.2 and 3.9 ms in 2 motoneurons. Possible pathways conducting these influences and their functional role are discussed.