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

这项研究首先考察了刺激前庭核(VN)复合体是否可以调节下颌有节奏的运动和颈部肌肉的有节奏的活动。重复电刺激口面部运动皮质，诱发有节奏的颌骨运动。在开口期或从开口期到闭口期的过渡过程中，脾肌肌电信号(SPEMG)显示有节律性的爆发。然而，在胸锁乳突部(StEMG)，肌电图在有节奏的下巴运动中没有显示任何爆发。在合颌期刺激前庭内侧核(MVN)可增加合颌运动的幅度，引起stEMG的一过性爆发，spEMG的活动持续时间延长。在张口期刺激MVN，扰乱了颌骨运动的节律，引起小的合口运动，短暂性肌电信号爆发，肌电信号出现抑制期。在张口期刺激上、外侧VN可增加张口运动的幅度。分别在合口期和开口期刺激下丘脑室旁核可降低合口期和开口期的动作幅度。这些结果表明，VN参与了下颌节律性运动和颈部肌肉活动的调节。然后进一步研究VN神经元在有节奏的下巴运动过程中的神经元活动。颌骨节律性运动是由机械刺激腭部粘膜引起的。在这些有节奏的下颌运动中，大约25%的VN神经元的放电频率显著增加，10%的VN神经元的放电频率显著降低。发放率的变化与颌骨节律性运动的阶段(张口期和闭口期)之间没有相关性。这些结果表明，VN神经元参与了控制颌骨运动。

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.