CONVERGENT CAROTID-SINUS NERVE AND SUPERIOR LARYNGEAL NERVE AFFERENT INPUTS TO NEURONS IN THE NTS

A population of 43 neurons in the nucleus of the solitary tract (NTS) was identified in pentobarbital sodium anesthetized, paralyzed, and ar tificially ventilated cats that received convergent inputs from caroti d sinus nerve (CSN) and superior laryngeal nerve (SLN) afferents. In 2 1 neurons, electrical stimulation of the CSN and SLN each evoked an ex citatory postsynaptic potential (EPSP; mean onset latency +/- SE of CS N-evoked input = 7.2 +/- 0.8 ms, range 2.1-14.1 ms; of SLN-evoked inpu t = 10.3 +/- 2.1 ms, range 2.8-46.8 ms). In 22 neurons, electrical sti mulation of either the CSN or SLN evoked an EPSP/inhibitory postsynapt ic potential (IPSP) sequence (CSN-evoked input = 6.7 +/- 0.6 ms, range 2.1-12.2 ms; SLN-evoked input = 8.4 +/- 0.8 ms, range 3.0-19.4 ms). S patial interactions (facilitation, summation, occlusion) and time-depe ndent inhibitory interactions were observed between the convergent inp uts. Natural stimulation of specific receptors indicated that 14 cells received a convergent excitatory input from carotid sinus barorecepto rs and laryngeal mechanoreceptors, 10 received a convergent excitatory input from carotid body chemoreceptors and laryngeal mechanoreceptors , and 5 received a convergent excitatory input from baroreceptors, che moreceptors, and laryngeal mechanoreceptors. The interactions and vari ous patterns of convergence suggest a significant integration of conve rgent inputs from disparate afferent sources by these neurons.