Reilmann R, Gordon A M, Henningsen H
Department of Biobehavioral Sciences, Teachers College, Columbia University, Box 199, 525 West 120th Street, New York, NY 10027, USA.
Exp Brain Res. 2001 Oct;140(4):443-52. doi: 10.1007/s002210100838.
The present study examined the initiation of digit contact and fingertip force development during whole-hand grasping. Sixteen healthy subjects grasped an object instrumented with force transducers at each digit and lifted it 10 cm. The grip (normal) and load (tangential) forces and the position of the object were recorded. Twenty-five lifts were performed with various object weights (300 g, 600 g, 900 g) and surface textures (sandpaper and rayon). Despite the large number of degrees of freedom, grip initiation with an object using the whole hand was characterized by stereotypical contact patterns, which are idiosyncratic to each subject across all object weights and textures. However, in spite of the initial asymmetric control, the forces were mainly synchronized by the occurrence of the peak grip and load force rates. The contribution of each digit to the total grip force decreased from radial to ulnar digits. The final force distribution was generally established already at the onset of load forces. Only subtle adjustments were seen thereafter, suggesting a fairly fixed force distribution pattern throughout the grasp. The findings suggest that, despite the large number of degrees of freedom in terms of contact initiation and force distribution in whole-hand grasping: (1) subjects employ preferred movement patterns to establish object contact with their digits, and (2) synchronize the subsequent force development and temporal coordination of the task. Thus while the complexity of the task requires control mechanisms beyond those seen in two-finger precision grasping, there are strategies to simplify the complex task of the initiation and development of fingertip forces in whole-hand grasping.
本研究考察了全手抓握过程中手指接触的起始和指尖力的发展。16名健康受试者抓握一个在每个手指上都装有力传感器的物体，并将其提起10厘米。记录握力（垂直方向）和负载力（切向）以及物体的位置。使用不同重量（300克、600克、900克）和表面纹理（砂纸和人造丝）的物体进行了25次提起操作。尽管存在大量自由度，但用全手抓握物体时，抓握起始具有刻板的接触模式，这种模式在所有物体重量和纹理条件下，每个受试者都是独特的。然而，尽管初始控制不对称，但力主要通过峰值握力和负载力速率的出现而同步。每个手指对总握力的贡献从桡侧手指向尺侧手指递减。最终的力分布通常在负载力开始时就已确定。此后仅观察到细微调整，这表明在整个抓握过程中力分布模式相当固定。研究结果表明，尽管在全手抓握的接触起始和力分布方面存在大量自由度：（1）受试者采用偏好的运动模式用手指建立与物体的接触，（2）同步后续的力发展和任务的时间协调。因此，虽然任务的复杂性需要超越两指精确抓握中所见的控制机制，但在全手抓握中存在简化指尖力起始和发展这一复杂任务的策略。
