Two virtual fingers in the control of the tripod grasp
Two virtual fingers in the control of the tripod grasp
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DOI：
10.1152/jn.2001.86.2.604
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发表时间：
2001-08-01
影响因子：
2.5
通讯作者：
Soechting, JF
中科院分区：
文献类型：
--
作者：
Baud-Bovy, G;Soechting, JF
为了研究多指抓握的组织，我们要求受试者用三个手指抓握物体：拇指、食指、中指或无名指。该物体有三个粗糙的平面接触面，其位置和方向是系统地变化的。受试者被要求抓住并举起物体，然后静止地握住它。我们分析了在静态保持期间记录的水平面中的抓握力。静态平衡要求三个手指施加的力在一个公共点相交，即力的焦点。由与拇指相对的两个手指施加的力的方向取决于两个手指的接触表面的取向，但不取决于拇指的接触表面的取向。拇指的力的方向不依赖于两个手指的接触表面的方向，并且仅微弱地依赖于拇指的接触表面的方向。一般来说，拇指的力量指向两个手指之间的中点。结果与三脚架抓取控制的分层模型一致。在第一级，在拇指和虚拟手指之间创建相对空间，虚拟手指大致位于两个实际手指之间的中间。由两个手指施加的力的方向被约束为关于相对轴镜像对称。在稳定性考虑的基础上，在下一个层次上阐述了手指力的实际方向。
To investigate the organization of multi-fingered grasping, we asked subjects to grasp an object using three digits: the thumb, the index finger, and the middle or ring finger. The object had three coarse flat contact surfaces, whose locations and orientations were varied systematically. Subjects were asked to grasp and lift the object and then to hold it statically. We analyzed the grasp forces in the horizontal plane that were recorded during the static hold period. Static equilibrium requires that the forces exerted by the three digits intersect at a common point, the force focus. The directions of the forces exerted by the two fingers opposing the thumb depended on the orientation of the contact surfaces of both fingers but not on the orientation of the contact surface of the thumb. The direction of the thumb's force did not depend on the orientation of the contact surfaces of the two fingers and depended only weakly on the orientation of the thumb's contact surface. In general, the thumb's force was directed to a point midway between the two fingers. The results are consistent with a hierarchical model of the control of a tripod grasp. At the first level, an opposition space is created between the thumb and a virtual finger located approximately midway between the two actual fingers. The directions of the forces exerted by the two fingers are constrained to be mirror symmetric about the opposition axis. The actual directions of finger force are elaborated at the next level on the basis of stability considerations.