Properties of postsynaptic potentials evoked in hypoglossal motoneurons by inferior alveolar nerve stimulation.

The properties of excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) produced in cat hypoglossal motoneurons by inferior alveolar nerve stimulation were studied. The percentage magnitude of a short- and a long-lasting component in inferior alveolar-induced IPSPs was measured by application of double shocks separated by 80- to 90-ms intervals to the inferior alveolar nerve. As a result, the protruder motoneurons received synaptic input primarily from the afferent fibers in both the ipsilateral and the contralateral inferior alveolar nerve generating the long-lasting IPSP. In addition, the retractor motoneurons received afferent fibers from the bilateral inferior alveolar nerves to generate the short- and the long-lasting IPSP. With respect to the properties of EPSPs, we have demonstrated that the amplitude of inferior alveolar-induced EPSPs decreased greatly with depolarization.