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Medullary swallowing-related neurons in the anesthetized cat

Umezaki, Toshiro1,2; Matsuse, Toshiaki1; Shin, Takemoto1

Motor Systems

SWALLOWING-RELATED neurons (SRNs) were recorded systematically in the medulla oblongata of urethane-anesthetized cats. The SRNs received orthodromic inputs from the superior laryngeal nerve (SLN) and showed transient changes in their activity synchronous with swallowing. These neurons could be divided into three types. Type I SRNs are sensory-relay neurons from the SLN in the nucleus of the tractus solitarius (NTS), type II are interneurons located diffusely in the parvo-cellular reticular formation ventral to the NTS, which received oligosynaptic inputs from the SLN, and type III are motoneurons in the nucleus ambiguus. Some type II neurons still showed the swallowing activity after the animals were paralysed, which suggests that they could be involved in the generation of swallowing outputs.

1Department of Otolaryngology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.

2Corresponding Author: Toshiro Umezaki

ACKNOWLEDGEMENTS: We thank Dr Alan D. Miller for helpful comments on an earlier version of the manuscript, and Dr T. Sugimoto for helping with statistical analysis and making figures. This study was supported by grants Nos. 04771280 and 06771420 from the Ministry of Education of Japan.

Received 3 March 1998; accepted 19 March 1998

© Lippincott-Raven Publishers.