Hand synergies during reach-to-grasp
Hand synergies during reach-to-grasp
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DOI：
10.1152/jn.2001.86.6.2896
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发表时间：
2001-12-01
影响因子：
2.5
通讯作者：
Ebner, TJ
中科院分区：
文献类型：
--
作者：
Mason, CR;Gomez, JE;Ebner, TJ
一个新兴的观点是，中枢神经系统使用协同作用来简化手的控制。先前的研究表明，静态的手部姿势可以用几个主成分来描述，其中高阶成分只解释了一小部分方差，但提供了有意义的信息。在早期工作的基础上，本研究探讨了整个抓握行为是否可以用少量的姿势协同作用来描述，以及这些协同作用在不同的抓握中是否相似。5名右撇子成人对16个不同的物体进行了五种类型的伸手抓握，包括力量抓握、举力抓握、精确抓握、模拟力量抓握和模拟精确抓握。物体的形状有锥体、圆柱体和纺锤形，系统地在尺寸上变化，以产生大范围的手指关节角度组合。利用四摄像头视频系统获得了手和手腕在伸手抓握过程中的21个位置的三维重建。在标记位置的时间序列上使用奇异值分解来识别每个任务的16个对象的共同模式（“特征姿态”）及其权重作为时间的函数。第一个特征姿态解释了手部形状方差的平均97.3 +/-0.89%（平均值+/- SD），第二个特征姿态解释了1.9 +/-0.85%。第一个特征姿态的特征是在伸手时张开和闭合的张开手构型。第二个特征姿势有助于控制拇指和长手指，特别是在伸手时张开手和准备抓握物体时闭合手。特征姿势和它们的时间演化在不同的科目和抓取中是相似的。高阶的特征姿势虽然只能解释少量的差异，但对手指和拇指的运动有贡献。这些发现表明，大部分的伸手抓握都是通过一种基本的姿势来实现的，随着时间的推移，手指和拇指的位置也会得到改进，从而产生独特的手部形状。
An emerging viewpoint is that the CNS uses synergies to simplify the control of the hand. Previous work has shown that static hand postures for mimed grasps can be described by a few principal components in which the higher order components explained only a small fraction of the variance yet provided meaningful information. Extending that earlier work, this study addressed whether the entire act of grasp can be described by a small number of postural synergies and whether these synergies are similar for different grasps. Five right-handed adults performed five types of reach-to-grasps including power grasp, power grasp with a lift, precision grasp, and mimed power grasp and mimed precision grasp of 16 different objects. The object shapes were cones, cylinders, and spindles, systematically varied in size to produce a large range of finger joint angle combinations. Three-dimensional reconstructions of 21 positions on the hand and wrist throughout the reach-to-grasp were obtained using a four-camera video system. Singular value decomposition on the temporal sequence of the marker positions was used to identify the common patterns ("eigenpostures") across the 16 objects for each task and their weightings as a function of time. The first eigenposture explained an average of 97.3 +/-0.89% (mean +/- SD) of the variance of the hand shape, and the second another 1.9 +/-0.85%. The first eigenposture was characterized by an open hand configuration that opens and closes during reach. The second eigenposture contributed to the control of the thumb and long fingers, particularly in the opening of the hand during the reach and the closing in preparation for object grasp. The eigenpostures and their temporal evolutions were similar across subjects and grasps. The higher order eigenpostures, although explaining only small amounts of the variance, contributed to the movements of the fingers and thumb. These findings suggest that much of reach-to-grasp is effected using a base posture with refinements in finger and thumb positions added in time to yield unique hand shapes.