Greenwood R, Hopkins A
Brain. 1976 Jun;99(2):375-86. doi: 10.1093/brain/99.2.375.
The electromyographic (EMG) response of soleus to a sudden fall has previously been shown to consist of two peaks of activity, the first a response to release, and the second in relation to landing (Greenwood and Hopkins, 1976). We have now examined activity in soleus during falls at various reduced accelerations. The amplitude of the first peak is proportional to acceleration and is not present during falls at accelerations of less than about 2-0 ms-2. The timing of the second peak is related to the timing of landing whether the duration of the fall depends upon the height or upon the acceleration of the fall. Its timing depends upon knowledge of the height of the fall, rather than to ongoing visual information, and upon labyrinthine function. EMG activity in soleus was also examined during voluntary downward steps which could be unexpectedly increased in height. The moment of landing is preceded by an increase of EMG activity and is followed by a number of peaks of activity. These peaks were not seen after the moment of expected landing during unexpectedly lengthened steps and thus probably represent reflex activity due to the mechanical event of landing.
先前的研究表明，比目鱼肌对突然下落的肌电图（EMG）反应包括两个活动峰值，第一个是对释放的反应，第二个与着地有关（格林伍德和霍普金斯，1976年）。我们现在研究了比目鱼肌在不同减速下落过程中的活动情况。第一个峰值的幅度与加速度成正比，在加速度小于约2.0米/秒²的下落过程中不存在。第二个峰值的时间与着地时间有关，无论下落持续时间取决于下落高度还是下落加速度。其时间取决于对下落高度的了解，而不是持续的视觉信息，还取决于内耳功能。我们还研究了比目鱼肌在自愿向下迈步过程中的EMG活动，这些迈步的高度可能会意外增加。着地瞬间之前EMG活动会增加，之后会出现多个活动峰值。在意外延长的迈步过程中，在预期着地瞬间之后没有看到这些峰值，因此这些峰值可能代表着地这一机械事件引起的反射活动。
