Studies on voluntary muscle relaxation and inhibitory control mechanism during human voluntary simultaneous bilateral muscular contraction

本文报道了利用松弛任务对人的自主活动进行抑制控制的研究。本研究有两个主要主题：第一个主题是考察力量输出的大小和肌肉收缩方式(张力逐渐增加或恒定张力施加)对运动抑制控制的影响。另一个主题是环绕抑制和半球间抑制。在这种情况下，研究对对侧同种肌肉的抑制效应，以比较单侧松弛和同时双侧松弛。由于每个研究由两个实验组成，因此本研究共进行了四个实验。这些实验的结果如下：1.松弛响应模式随力输出的大小而变化。松弛潜伏期与用力输出的大小有明显的相关性。张力开始减小的时间不受输出力大小的影响。抑制指令从刺激的呈现开始在恒定的时间发出。然而，当肌肉收缩非常剧烈时，由于指令不能完全抑制肌肉活动，放松的反应时间延长。在追求斜波目标的过程中，随着肌肉力量的逐渐增强，反应时随斜波频率的增加而延长。同时双侧收缩的松弛与单边收缩的松弛不同。当双侧用力时只放松一侧力量时，对侧张力曲线略有上升。这一现象似乎是由于大脑半球间抑制的解除所致。

Studies on inhibitory control in human voluntary movements were reported by mean of the task of relaxation. There are two main themes in the present research; the first theme is to investigate the influences of the magnitude of force output and mode of muscle contraction (gradual increment for tension or constant tension exertion) on inhibitory control of movement. The other theme is surround inhibition and interhemispheric inhibition. In this case inhibitory effects to the contralateral homologous muscle are investigated to compare unilateral relaxation with the simultaneous bilateral one. As each research is consisted of two experiments, total 4 experiments were conducted in the present studies. The results are derived from these experiments as follows:1. Response patterns of relaxation are varied according to the magnitude of force output.2. The latency of relaxation is clearly related with the magnitude of force output.3. The time for the initiation of decrement of tension is not affected by the magnitude of force output.4. The inhibition command is issued at a constant time from the presentation of the stimulus. However, since the command cannot completely inhibit the muscle activity when the muscle contraction is very intense, reaction times for relaxation are prolonged.5. When the muscle strength is gradually increased in pursuit of the ramp wave target, reaction times are prolonged as the frequency of the ramp wave heightened.6. Relaxation from simultaneous bilateral contraction is different from those of the unilateral.7. When only unilateral strength is relaxed during bilateral strength exertion, the contralateral tension curve is slightly rised. It seems that this phenomenon is due to the removal of the interhemispheric inhibition.