Force sharing among fingers as a model of the redundancy problem
Force sharing among fingers as a model of the redundancy problem
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DOI：
10.1007/s002210050343
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发表时间：
1998-04-01
影响因子：
2
通讯作者：
Zatsiorsky, VM
中科院分区：
文献类型：
--
作者：
Li, ZM;Latash, ML;Zatsiorsky, VM
这项研究的目的是验证伯恩斯坦的观点，即运动协同为运动冗余问题提供解决方案。一只手的单个手指产生的力被记录在一个、两个、三个和四个手指的任务中。受试者(n=10)被要求产生最大总力(最大自愿收缩，MVC)，并使用不同的手指组合匹配坡道总力轮廓。我们发现，在多指MVC任务中，单个指力比单指任务中的小。赤字随着受累手指数量的增加而增加。观察到饱和效应：当涉及多个效应器时，添加新的效应器不会显著改变总力输出。数据证实了这样一种观点，即达到协同效应水平的中枢神经驱动有一定的限制，是不能超过的上限。中枢神经系统不能同时最大限度地激活服务于所有手指的肌肉。其次，在坡道试验过程中，单个手指产生的力是线性相关的。因此，在审判开始时就建立了力量分担模式，在坡道期间没有改变。提出了一个假设，即手指之间的力分布可以被组织起来，以使相对于手的功能纵轴的不必要的旋转力矩最小化。最后，在四指测试中，连续10次尝试的总最大力量输出的方差小于最大单指力量的方差之和。这一发现表明，所研究的运动任务的控制系统至少包括两个水平，即中枢神经驱动水平和协同水平。在协同水平上，观察到个体指力产生的相互补偿。
The aim of this study was to test Bernstein's idea that motor synergies provide solutions to the motor redundancy problem. Forces produced by individual fingers of one hand were recorded in one-, two-, three-, and four-finger tasks. The subjects (n=10) were asked to produce maximal total force (maximal voluntary contraction, MVC) and to match a ramp total force profile using different combinations of fingers. We found that individual finger forces were smaller in multifinger MVC tasks than in single-finger tasks. The deficit increased with the number of fingers involved. A saturation effect was observed: when several effecters were involved, adding a new effector did not significantly change the total force output. The data confirmed the idea that the central neural drive arriving at the level of synergies has a certain limit, a ceiling, that cannot be exceeded. The central nervous system cannot maximally activate the muscles serving all the fingers at the same time. Secondly, during the course of ramp trials, forces produced by individual fingers were linearly related to each other. Hence, a force sharing pattern was established at the beginning of the trial and did not change during the ramp period. A hypothesis is suggested that force distribution among fingers may be organized so as to minimize unnecessary rotational moment with respect to the functional longitudinal axis of the hand. Finally, in the four-finger trials, variance of the total maximal force output in ten consecutive attempts was smaller than the sum of variances of the maximal individual finger forces. The finding suggests that the control system of the motor tasks studied involves at least two levels, a central neural drive level and a synergy level. At the synergy level, an intercompensation in individual finger force production is observed.