2006 Fiscal Year Final Research Report Summary
Localization and functional role of interneurons in the brainstem involved in chewing and swallowing
| Project/Area Number |
17591934
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional basic dentistry
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| Research Institution | Niigata University |
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Principal Investigator |
INOUE Makoto Niigata University, Institute of Medicine and Dentistry, Associate Professor, 医歯学系, 助教授 (00303131)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMURA Kensuke Niigata University, Institute of Medicine and Dentistry, Associate Professor, 医歯学系, 助教授 (90272822)
YAMADA Yoshiaki Niigata University, Institute of Medicine and Dentistry, Professor, 医歯学系, 教授 (80115089)
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| Project Period (FY) |
2005 – 2006
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| Keywords | mastication / swallow / jaw opening reflex / inferior alveolar nerve / tongue / jaw muscle / electromyography |
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| Research Abstract |
An electrophysiological study was performed in awake and anesthetized animals as well as human subjects. In animal experiments, interneuron activities in the brainstem were recorded with EMGs of masseter, digastric and genioglossus muscles. Electrical stimulation was applied in the inferior alveolar and superior laryngeal nerves to evoke the jaw reflex and swallowing reflex, respectively, while the cortical masticatory area was also stimulated to evoke the fictive mastication. Interneuron and/or muscle activity was recorded to investigate how they were modulated by the peripheral/central stimulation. It was very difficult to record interneuron activity because they were very sensitive to the respiration which was also modulated by the stimulation. We, therefore, moved our eyes to the output system to understand the function. In chronic experiments of animals, changes in jaw reflex responses were evaluated during chewing and swallowing. The results showed that the reflexes were suppressed not only during chewing but also during swallowing, and the modulation during swallowing was moderate as compared to that during chewing. The results suggest that the modulatory inputs to motoneurons exist from the chewing center and swallowing center independently. On the other hand, in humans, modulatory pattern was investigated in the EMG activity of the genioglossus muscle which was one of the extrinsic tongue muscles and was known to critically function as making the food bolus and transporting it through the oropharynx to the esophagus. the anterior and posterior portions of tongue were modulated by the peripheral inputs in a different manner. It may contribute to completion of ingestion.
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