Responses of inferior salivatory neurons to stimulation of trigeminal sensory branches.

A total of 84 single inferior salivatory neurons was identified by antidromic stimulation of the tympanic nerve. Their responsiveness was tested to stimulation of the ipsilateral infraorbital, lingual, and inferior alveolar nerves in urethane-chloralose-anesthetized cats. The conduction velocities of preganglionic fibers of inferior salivatory neurons ranged from 2.2 to 9.1 m/s, and 54% of those neurons responded with spikes to stimulation of at least one of the infraorbital, lingual, or inferior alveolar nerves (responsive type neurons). The latencies of spike responses to stimulation of the trigeminal sensory branches ranged from 4.0 to 21.0 ms, which were shorter than those of superior salivatory neurons. Impulses of both A-beta and A-delta afferent fibers of the trigeminal nerve were found to be effective for activation of inferior salivatory neurons. The convergence of excitatory inputs from more than one sensory nerve was found in most of the responsive type neurons (73%).