A study in the strategy for motor control of human masticatory system -Intensity and frequency-

7名老年人(平均年龄71.6岁)在0.3赫兹、1.3赫兹和随机频率的重复恒频信号的控制下进行了敲击下颌的动作。观察咬肌肌电(Mm)、下颌运动图、冲击加速度、指令信号之间的关系。1.老年有牙组各项参数值与老年无牙组差异较大。2.即刻敲击动作的平均间隔时间：老年组为709毫秒，老年组为976毫秒，青少年组为691毫秒。3.指令信号与毫米爆裂的时间间隔：在0.3赫兹的7~30次试验中，这些值介于130~150毫秒(老年有牙组持续出现上述时间)和30~50毫秒(年轻有牙组持续出现上述时间)之间。在实验1~6时，他们的AN频率值降低。指令信号与咬合牙接触时差：1.3 Hz时，老年有牙组与其他组的指令信号接触时间一致。在0.3赫兹时，这些值与之前的参数几乎相同。4.冲击加速度：从试验1到试验30，An条件下的数值略有增加，0.3赫兹的数值变化很大。5.总结如下：电机控制策略中的三组反馈控制和前馈控制的比例不同。我们可以在0.3赫兹看到它，这是很难执行的，特别是在撞击加速时。

Seven elderly dentulous people (mean age 71.6) performed jaw-tapping movements commanded by repetitive constant frequency signals at 0.3 Hz, 1.3 Hz and ad-lib. Observation was made on the relation among Masseteric muscle EMG (Mm), Mandibular Kinegiogram, impact acceleration, and command signal. 1. All parameter values of elderly dentulous group varied widely like elderly edentulous group. 2. Average intervals of ad-lib tapping movements are 709 msec (elderly dentulous group), 976 msec (elderly group wearing FD), 691 msec (dentulous young adults). 3. The time lag between command signal and Mm burst onset: At trials 7〜30 of 0.3 Hz these values varied between 130〜150 msec ( elderly dentulous group constantly showed about as long as these ) and 30〜50 msec ( young dentulous group constantly showed about as long as these ). At trials 1〜6 their values of an frequencies decreased. The time lag between command signal and occlusal tooth contact: At 1.3 Hz elderly dentulous group made their occlusal tooth contact time correspond with command signals like other groups. At 0.3 Hz those values were almost as same as previous parameter. 4. Impact acceleration: Values at an conditions were increasing a little from trial 1 to 30 and values at 0.3 Hz varied widely. 5. It can be summarized as follows: Three groups in strategy of motor control differ in the ratio of feedback control and feedforward control. We can see it at 0.3 Hz, which it is difficult to perform and especially at impact acceleration.