The difference pattern of regulation by muscle spindles during the various cortically-induced rhythmic movements.

为阐明咀嚼力的控制机制，我们在麻醉家兔皮层诱导的节律性下颌运动（CRJMs）过程中，同步观察了三叉神经中脑核（MesV）梭形传入神经元的放电，并与咀嚼肌肌电和下颌运动进行了对比分析。此外，我们研究了咀嚼测试条之前和期间的EMG信号之间的差异的开始。在CRJM过程中，制备了五种不同硬度的聚氨酯泡沫测试条，并将其插入相对的磨牙之间。将牙周感觉和/或肌肉感觉去传入后进行类似的记录。咀嚼肌肌电爆发的综合活动度和持续时间也随肌条硬度的增加而增加.所有记录到的传入神经均随下颌运动而节律性放电，且随着材料硬度的增加，下颌闭合期的脉冲数增加.评价咀嚼咀嚼条时咬肌肌电反应的起始时间，咀嚼条咀嚼肌肌电反应的起始时间在咀嚼条咀嚼力起始前或咀嚼条咀嚼肌肌电反应的最短潜伏期的时间间隔前.在早期反应（如3所述）中，咬肌肌电反应的起始行为如下：（1）它不受条硬度的影响。(2)牙周膜传入神经的去神经支配不改变这一点。(3)肌梭传入阻滞了咀嚼肌的前馈，提示肌梭活动参与了咀嚼肌的前馈机制。

To elucidate mechanisms of controlling masticatory force, we analyzed the discharges of spindle affertents in the mesencephalic trigeminal nucleus (MesV) simultaneously with masticatory muscle EMGs and jaw movements during cortically induced rhythmic jaw movements (CRJMs) in anesthetized rabbits. In addition, we investigated the onset of the difference between the EMG signals of both before and during the chewing of test strip. Five test strips of polyurethane foam of different hardness were prepared and inserted between the opposing molars during CRJMs. Similar recordings were made after deafferentation of periodontal and/or muscle sensations.Results obtaind were as follows :1. The integrated activity and duration of the masseteric EMG bursts also increased with strip hardness.2. All recorded afferents dischrged rhythmically in reration to jaw movements, and the number of impulse during the jaw-closing phase increased with increasing the hardness of the materials.3. The onset of the masseteric EMG response to the chewing of strip was evaluated, and it was occasionaly before the force onset or time lapse of the shortest latency for the jaw-stretch reflex.4. In the early response (as described in 3), the behavior of the onset of the masseteric EMG response was as follows :(1) It was not changed by strip hardness.(2) It was not changed by the denervation of periodontal afferents.(3) It was delayd by the deafferentation of muscle spindle afferents.These results suggest that the muscle spindle activity is involved in the feedforward machanism during chewing.