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

点击翻译按钮获取中文摘要

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.