Yoneda Masaki, Saitoh Kazuya
Arts and Sports Education, Graduate School of Education, Kumamoto University, 2-40-1, Kurokami, Chuo-ku, Kumamoto-shi, Kumamoto, Japan.
Lifelong Sports and Welfare Course, Faculty of Education, Kumamoto University, 2-40-1 Kurokami, Chuo-ku, Kumamoto-shi, Kumamoto, 860-8555, Japan.
Dysphagia. 2018 Jun;33(3):358-368. doi: 10.1007/s00455-017-9860-9. Epub 2017 Nov 2.
Modification of movements by proprioceptive feedback during mastication has an important role in shifting from the oral to the pharyngeal phase of swallowing. The aim of this study was to investigate the kinetics of masticatory muscles throughout a sequence of oropharyngeal swallowing and to present a hypothetical model of the involvement of the nervous system in the transition from mastication to the swallowing reflex. Surface electromyographic signals were recorded from the jaw-closing masseter muscles and the jaw-opening suprahyoid muscle group when a piece of bread (3-5 g) was ingested. Participants were not provided any additional instruction regarding how to chew and swallow. In the final stage of mastication, compared with other stages of mastication, the duration between sequential peak times of rhythmic activity of the masseter muscles was prolonged. Electromyography revealed no significant change in the suprahyoid muscle group. Accordingly, contraction of the jaw-closing muscles and the jaw-opening muscles altered from out-of-phase to in-phase. We have presented a hypothetical model based on the results of the present study, in which mastication shifts to the swallowing reflex when feed-forward inputs from rhythm generators for the jaw-closing and the jaw-opening muscles converge onto an assumed "convertor" neuron group concurrently. This model should contribute to understanding the pathophysiology of dysphagia.
咀嚼过程中本体感觉反馈对运动的调节在从吞咽的口腔期向咽期转变中起着重要作用。本研究的目的是研究在一系列口咽吞咽过程中咀嚼肌的动力学，并提出一个关于神经系统在从咀嚼过渡到吞咽反射过程中所起作用的假设模型。当摄入一片面包（3 - 5克）时，记录下颌闭合咬肌和下颌张开舌骨上肌群的表面肌电信号。未向参与者提供任何关于如何咀嚼和吞咽的额外指导。在咀嚼的最后阶段，与咀嚼的其他阶段相比，咬肌节律性活动连续峰值时间之间的持续时间延长。肌电图显示舌骨上肌群无明显变化。因此，下颌闭合肌和下颌张开肌的收缩从异相变为同相。我们基于本研究结果提出了一个假设模型，即当下颌闭合肌和下颌张开肌节律发生器的前馈输入同时汇聚到一个假定的“转换”神经元群时，咀嚼转变为吞咽反射。该模型应有助于理解吞咽困难的病理生理学。
