The nature and postnatal development of reflex deglutition in the kitten.

Abstract

1. The nature and course of postnatal development of reflex deglutition were investigated by means of the single fiber recordings from the motor fibers of hypoglossal, accessory and phrenic nerves in unanesthetized, midcollicularly decerebrate cats and kittens of various postnatal periods.2. The motor fibers of kitten hypoglossal nerve showed a great deal of variety of patterns of discharge during swallowing depending on the differences of the nerve fiber, the squirt of water into the oropharynx, the type of mechanical stimulation and the ventilatory state of the animal. The burst discharge was also produced in the nerve fiber innervating the muscles having no direct participation in the act of swallowing.3. Gallamine-induced motoparalysis modified profoundly the pattern of the motor nerve fiber discharges both during swallowing and during electrical stimulation of the superior laryngeal nerve in the kitten.4. The hypoglossal motor fibers which revealed the “swallowing discharge” in normal conditions produced the respiratory volleys when the animal was asphyxiated, whereas the phrenic motor fibers discharging rhythmically in phase with respiration produced the “swallowing discharge” (a complete silence in a few fibers) when a small amount of water was squirted into the oropharynx or the superior laryngeal nerve was stimulated electrically by repetitive pulses.5. The response features of the motor nerve fibers of kitten hypoglossal nerve during swallowing gradually approached to those of the adult cats with the lapse of time in approximately 3 months postnatally.