Neural control of hyperactivity and spasm in the masticatory muscles.

认为颞下颌关节紊乱病是咀嚼肌过度活动或痉挛所致。但其神经机制至今尚未完全阐明。为了研究这种机制，我们做了以下六个实验。(1)食物硬度对咀嚼力控制的影响。(2)肌梭传入在咀嚼力控制中的作用。(3)（4）下颌肌梭传入的分类;（5）生物胺对三叉神经运动神经元膜特性的影响;（6）味觉排斥行为与唾液分泌的关系。(2)观察咀嚼肌梭形传入纤维放电频率与咀嚼力大小的相关性。(3)咀嚼肌不同阶段的放电模式的差异可能是由于咀嚼肌的梭动活动和颌骨运动模式的阶段依赖性调制。(4)我们发现，下颌肌梭传入可能被分为两组的基础上的放电模式的斜坡和保持拉伸反应的可能性。(5)细胞内钙离子浓度可调节生物胺对三叉神经运动神经元后去极化的影响。(6)臂旁核可能在味觉刺激引起的流涎反应中起重要作用。

It is suggested that hyperactivity or spasm in the masticatory muscles cause the temporomandibular joint disorders. However the neural mechanism of the hyperactivity has not bee found clealy. To investigate this mechanism we have done following six experiments. (1) effect of the hardness of food on the control of masticatory force. (2) role of the muscle spindle afferents on the control of masticatory force. (3) modulation of jaw muscle spindle discharge during mastication in the awake animals (4) classification of the jaw muscle spindle afferents (5) influence of the biogenic amine on the membrane charactaristics of the trigeminal motoneurons (6) relationship between the taste rejection behavior and salivation.Results were as follows :(1) During cortically induced rhythmic jaw movements (CRJMs) in anesthetized rabbits, chewing of the harder test strips induced the larger EMG activities of the jaw closing muscle. (2) We observed the correlation between the magnitude of the masticatory force and the firing frequency of the spindle afferent of masticatory muscle. (3) The difference in the firing pattern among masticatory stages may be ascribed to a stage-dependent modulation of both fusimotor activity and jaw movement pattern. (4) We found the possibility that the jaw muscle spindle afferents may be calssified into two groups on the basis of the firing pattern in the response to the ramp-and-hold stretch. (5) Intracellular calcium concentration may modulate the effect of the biogenic amine on the afterdepolarization in the trigeminal motoneurons. (6) The parabrachial nucleus may play an important role on salivation induced by the rejectable taste.