Elucidation of control mechanisms of oral, facial, tongue sensation and jaw, facial, head movements during mastication

本研究首先探讨是否前庭核（VN）复合体的刺激可以调节有节奏的下颌运动和颈部肌肉的节奏活动。通过重复电刺激口面运动皮层来诱导有节奏的下颌运动。在夹肌肌电图（spEMG）显示有节奏的爆发，在下巴打开阶段或从下巴打开阶段的过渡到下巴关闭阶段。然而，在胸锁乳突肌（stEMG）中，在有节奏的下颌运动期间，肌电图没有显示任何爆发。刺激前庭内侧核（MVN）在下颌闭合阶段的下颌闭合运动的幅度增加，诱导stEMG中的短暂爆发，并在spEMG中的活动的持续时间增加。在下颌张开阶段刺激MVN扰乱了下颌运动的节奏，诱导了一个小的下颌闭合运动，stEMG中的短暂爆发和spEMG中的抑制期。刺激的上级和外侧VN在下颌打开阶段增加了下颌打开运动的幅度。在下颌闭合和张开阶段刺激下VN分别降低了下颌闭合和张开运动的幅度。这些结果表明VN参与了节律性下颌运动和颈部肌肉活动的调节。进一步的研究，然后检查VN神经元的神经元活动在有节奏的下颌运动。通过机械刺激腭粘膜诱导有节奏的下颌运动。约25%的VN神经元的放电率显着增加，10%的VN神经元的放电率显着下降，在这些有节奏的下颌运动。有没有相关性之间的变化，在射击率和相位的有节奏的下颌运动（下颌打开和下颌关闭阶段）。这些结果表明，VN神经元参与控制颌骨运动。

This study first examines whether stimulation of the vestibular nuclear (VN) complex can modulate rhythmic jaw movements and the rhythmic activity of the neck muscles. Rhythmic jaw movements were induced by repetitive electrical stimulation of the orofacial motor cortex. An electromyogram in the splenius muscles (spEMG) showed rhythmic bursts during the jaw-opening phase or during the transition from the jaw opening phase to the jaw-closing phase. In the sternomastoid (stEMG), however, the electromyogram did not show any bursts during rhythmic jaw movements. Stimulation of the medial vestibular nucleus (MVN) during the jaw-closing phase increased the amplitude of the jaw-closing movement, induced a transient burst in the stEMG, and the duration of activity in the spEMG was increased. Stimulation of the MVN during the jaw-opening phase disturbed the rhythm of jaw movements, induced a small jaw-closing movement, a transient burst in the stEMG and an inhibitory period in the spEMG. Stimulation of the superior and the lateral VN during the jaw-opening phase increased the amplitude of the jaw opening movement. Stimulation of the inferior VN during the jaw-closing and the jaw-opening phase respectively decreased the amplitude of the jaw-closing and the jaw-opening movements. These results imply that the VN is involved in the modulation of rhythmic jawmovements and neck muscle activities. A further study then examines the neuronal activities of the VN neurons during rhythmic jaw movements. Rhythmic jaw movements were induced by mechanical stimulation of the palate mucosa. The firing rate of approximately 25% of VN neurons increased significantly, and that of 10% of VN neurons decreased significantly, during these rhythmic jaw movements. There was no correlation between the change in the firing rate and the phase of the rhythmic jaw movements (jaw-opening and jaw-closing phases). These results suggest that the VN neurons areinvolved in controlling jaw movements.