Department of Neurological, Neuropsychological, Morphological and Movement Sciences, University of Verona, Italy.
Neuroscience. 2010 Nov 24;171(1):205-13. doi: 10.1016/j.neuroscience.2010.08.023. Epub 2010 Sep 9.
We wanted to determine whether movement planning followed Fitts' law by investigating the relationship between movement planning and movement performance in experienced dancers executing a typical classical ballet step in which the big toe was pointed to targets at different distances and of different widths so as to obtain several indices of difficulty (ID). Movement time, velocity and variability at the target were the variables of movement performance kinematics; movement planning was evaluated by analysis of anticipatory postural adjustments (APAs) to assess their modulation at different IDs. Movement time and peak of velocity were found to scale with the ID only when individual movement distance across target widths was entered into the analysis. APA magnitude and duration both scaled according to movement parameters but not in the same way. APA magnitude scaled with movement velocity, while APA duration was sensitive to the amplitude-to-accuracy ratio following the ID for movements performed in the shortest time interval when on-line feedback control is probably not available. Here we show that timing of muscle activation acts as an independent central command that triggers fine-tuning for speed-accuracy trade-off.
我们希望通过研究经验丰富的舞者在执行典型的古典芭蕾舞步时的运动规划与运动表现之间的关系，来确定运动规划是否遵循菲茨定律，在这个舞步中，大脚趾指向不同距离和不同宽度的目标，从而获得几个难度指数（ID）。运动时间、速度和在目标处的可变性是运动表现运动学的变量；通过分析预期姿势调整（APAs）来评估它们在不同 ID 下的调节，以此来评估运动规划。只有当将个体在目标宽度上的运动距离纳入分析时，运动时间和速度峰值才与 ID 相关。APA 的幅度和持续时间都根据运动参数进行缩放，但方式不同。APA 幅度与运动速度相关，而 APA 持续时间则对 ID 后运动的幅度-准确性比敏感，因为在最短的时间间隔内执行运动时，在线反馈控制可能不可用。在这里，我们表明肌肉激活的定时作为一个独立的中央命令，触发了速度-准确性权衡的微调。
