EFFECT OF STIMULATING PERIPHERAL AND CENTRAL NEURAL PATHWAYS ON PHARYNGEAL MUSCLE-CONTRACTION TIMING DURING SWALLOWING IN DOGS

The effect of stimulating peripheral and central neural pathways on th e electromyographic activity in the hyopharyngeal, thyropharyngeal, an d cricopharyngeal muscles was studied in eight dogs during 1) eating, 2) unilateral electrical stimulation of the superior laryngeal nerve, and 3) unilateral electrical stimulation of the solitary nucleus. The duration of pharyngeal swallowing was significantly shorter during eat ing than during stimulation of the solitary nucleus in the anesthetize d dog (mean difference 127 ms, SEM 9, n = 15). The duration of pharyng eal swallowing was significantly shorter during eating than during sti mulation of the superior laryngeal nerve in the awake dog (mean differ ence 84 ms, SEM 13, n = 9), The duration of pharyngeal swallowing duri ng stimulation of the superior laryngeal nerve under anesthesia was si gnificantly shorter than during stimulation of the solitary nucleus un der anesthesia (mean difference 58 ms, SEM 18, n = 9), The difference in duration of pharyngeal swallowing during stimulation of the superio r laryngeal nerve between the awake state and during anesthesia was no t significant (mean 19 ms, SEM 14, n = 9), It was concluded that stimu lation of peripheral and central neural pathways resulted in different pharyngeal muscle contraction timing during swallowing in dogs. (C) 1 998 Elsevier Science Inc.