Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy.
Front Comput Neurosci. 2013 Aug 7;7:107. doi: 10.3389/fncom.2013.00107. eCollection 2013.
What sources of information and what control strategies the central nervous system (CNS) uses to perform movements that require accurate sensorimotor coordination, such as catching a flying ball, is still debated. Here we analyzed the EMG waveforms recorded from 16 shoulder and elbow muscles in six subjects during catching of balls projected frontally from a distance of 6 m and arriving at two different heights and with three different flight times (550, 650, 750 ms). We found that a large fraction of the variation in the muscle patterns was captured by two time-varying muscle synergies, coordinated recruitment of groups of muscles with specific activation waveforms, modulated in amplitude and shifted in time according to the ball's arrival height and flight duration. One synergy was recruited with a short and fixed delay from launch time. Remarkably, a second synergy was recruited at a fixed time before impact, suggesting that it is timed according to an accurate time-to-contact estimation. These results suggest that the control of interceptive movements relies on a combination of reactive and predictive processes through the intermittent recruitment of time-varying muscle synergies. Knowledge of the dynamic effect of gravity and drag on the ball may be then implicitly incorporated in a direct mapping of visual information into a small number of synergy recruitment parameters.
中枢神经系统（CNS）用于执行需要精确感觉运动协调的运动的信息来源和控制策略是什么，这仍然存在争议。在这里，我们分析了六个被试在从 6 米的距离正面接住球时，记录的来自 16 个肩部和肘部肌肉的肌电图（EMG）信号，球到达的高度和飞行时间不同（550、650、750 毫秒）。我们发现，肌肉模式的很大一部分变化可以通过两个时变的肌肉协同作用来捕获，即协调具有特定激活波形的肌肉群的募集，根据球的到达高度和飞行时间来调节幅度和时间。一个协同作用从启动时间开始以短的固定延迟募集。值得注意的是，第二个协同作用在撞击前的固定时间募集，这表明它是根据准确的接触时间估计来定时的。这些结果表明，拦截运动的控制依赖于通过时变肌肉协同作用的间歇性募集来结合反应和预测过程。那么，对球的重力和阻力的动态影响的了解可能会被隐含地纳入到将视觉信息直接映射到少数几个协同作用募集参数中。
