Author(s)
Yoichiro Sugiyama
Shinya Fuse
Keiko Hashimoto
Shigeyuki Mukudai
Shigeru Hirano
Affiliation(s)
Kyoto Prefectural University of Medicine
Abstract:
Objective: The pharyngeal stage of swallowing consists of well-coordinated and stereotyped movements of the pharyngeal and laryngeal muscles. However, in terms of rheological characteristics, the bolus transit through the alimentary tract seems to be altered depending on its viscosity and volume, which might be recognized as the relative effects of sensory feedback on the swallowing pattern regulation. In order to investigate whether the pattern generation of the oropharyngeal swallow could be influenced by laryngeal afferent inputs during swallowing, we recorded the activity of swallowing-related neurons in the medulla during fictive swallowing with or without laryngeal sensory stimulation in perfused rats.Method: The animals were decerebrated and then perfused with artificial cerebrospinal fluid. The activities of the phrenic and the vagus nerves were recorded to identify respiration and swallowing. Stimulation of the superior laryngeal nerve was used to elicit swallowing. The activity of the swallowing-related neurons during fictive swallowing concomitant with repetitive stimulation of the superior laryngeal nerve was compared that without laryngeal sensory stimulation.Results: Many swallowing interneurons did not significantly change in firing frequency by repetitive stimulation of laryngeal afferents during swallowing.Conclusion: The pharyngeal stage of swallowing would be strictly controlled by the central regulatory mechanisms that generate its intrinsic motor pattern, resulting in prevention of functional instability of swallowing.