van de Kamp Cornelis, Zaal Frank T J M
Center for Human Movement Sciences, University of Groningen, PO Box 196, 9700 AD Groningen, The Netherlands.
Exp Brain Res. 2007 Sep;182(1):27-34. doi: 10.1007/s00221-007-0968-2. Epub 2007 May 22.
Prehension has traditionally been seen as the act of coordinated reaching and grasping. However, recently, Smeets and Brenner (in Motor Control 3:237-271, 1999) proposed that we might just as well look at prehension as the combination of two independently moving digits. The hand aperture that has featured prominently in many studies on prehension, according to Smeets and Brenner's "double-pointing hypothesis", is really an emergent property related to the time course of the positions of the two digits moving to their respective end points. We tested this double-pointing hypothesis by perturbing the end position of one of the digits while leaving the end position of the opposing digit unchanged. To this end, we had participants reach for and grasp a metallic object of which the side surfaces could be made to slide in and out. We administered the perturbation right after movement initiation. On several occasions, after perturbing the end position of one digit, we found effects also on the kinematics of the opposing digit. These findings are in conflict with Smeets and Brenner's double-pointing hypothesis.
传统上，抓握被视为协调伸手和抓取的行为。然而，最近，斯米茨和布伦纳（发表于《运动控制》第3卷：第237 - 271页，1999年）提出，我们不妨将抓握视为两个独立移动手指的组合。根据斯米茨和布伦纳的“双指假说”，在许多抓握研究中显著出现的手部开口，实际上是一种与两个手指向各自端点移动的时间进程相关的涌现特性。我们通过扰动其中一个手指的端点位置，同时保持相对手指的端点位置不变，来检验这个双指假说。为此，我们让参与者伸手去抓握一个金属物体，该物体的侧面可以使其滑进滑出。我们在运动开始后立即施加扰动。有几次，在扰动一个手指的端点位置后，我们发现对相对手指的运动学也有影响。这些发现与斯米茨和布伦纳的双指假说相冲突。
