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

通过放松任务对人类自主运动的抑制控制进行了研究。目前的研究主要有两个主题；第一个主题是研究力量输出的大小和肌肉收缩的方式（张力逐渐增加或持续张力施加）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，研究了对侧同源肌的抑制作用，以比较单侧松弛和双侧同时松弛。由于每项研究由两个实验组成，因此本研究共进行了4个实验。实验结果如下：1。松弛的响应模式随力输出的大小而变化。松弛的潜伏期与输出力的大小有明显的关系。张力开始衰减的时间不受输出力大小的影响。抑制指令是在刺激出现后的固定时间发出的。然而，当肌肉收缩非常强烈时，由于指令不能完全抑制肌肉活动，因此放松的反应时间延长。当肌肉力量逐渐增加以追求斜坡波目标时，反应时间随着斜坡波频率的增加而延长。同时双侧收缩引起的松弛不同于单侧收缩引起的松弛。当双侧力量发挥时仅放松单侧力量时，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消除。

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.