Rouse Adam G, Schieber Marc H
Department of Neurology, University of Rochester, Rochester, New York; Department of Neurobiology and Anatomy, University of Rochester, Rochester, New York; and Department of Biomedical Engineering, University of Rochester, Rochester, New York.
Department of Neurology, University of Rochester, Rochester, New York; Department of Neurobiology and Anatomy, University of Rochester, Rochester, New York; and Department of Biomedical Engineering, University of Rochester, Rochester, New York
J Neurophysiol. 2015 Dec;114(6):3268-82. doi: 10.1152/jn.00686.2015. Epub 2015 Oct 7.
In reaching to grasp an object, the arm transports the hand to the intended location as the hand shapes to grasp the object. Prior studies that tracked arm endpoint and grip aperture have shown that reaching and grasping, while proceeding in parallel, are interdependent to some degree. Other studies of reaching and grasping that have examined the joint angles of all five digits as the hand shapes to grasp various objects have not tracked the joint angles of the arm as well. We, therefore, examined 22 joint angles from the shoulder to the five digits as monkeys reached, grasped, and manipulated in a task that dissociated location and object. We quantified the extent to which each angle varied depending on location, on object, and on their interaction, all as a function of time. Although joint angles varied depending on both location and object beginning early in the movement, an early phase of location effects in joint angles from the shoulder to the digits was followed by a later phase in which object effects predominated at all joint angles distal to the shoulder. Interaction effects were relatively small throughout the reach-to-grasp. Whereas reach trajectory was influenced substantially by the object, grasp shape was comparatively invariant to location. Our observations suggest that neural control of reach-to-grasp may occur largely in two sequential phases: the first determining the location to which the arm transports the hand, and the second shaping the entire upper extremity to grasp and manipulate the object.
在伸手抓取物体时，手臂将手运送到预期位置，同时手会做出抓握物体的形状。先前追踪手臂端点和抓握孔径的研究表明，伸手和抓握虽然并行进行，但在一定程度上相互依赖。其他关于伸手和抓握的研究，在手部做出抓握各种物体的形状时，研究了所有五根手指的关节角度，但没有同时追踪手臂的关节角度。因此，我们在一项分离了位置和物体的任务中，研究了猴子在伸手、抓握和操作过程中从肩部到五根手指的22个关节角度。我们量化了每个角度随位置、物体及其相互作用而变化的程度，所有这些都是时间的函数。尽管关节角度在运动早期就因位置和物体而有所不同，但从肩部到手指的关节角度的位置效应早期阶段之后，是一个后期阶段，其中物体效应在肩部远端的所有关节角度中占主导地位。在整个伸手抓握过程中，相互作用效应相对较小。虽然伸手轨迹受物体的影响很大，但抓握形状相对不受位置的影响。我们的观察结果表明，伸手抓握的神经控制可能主要发生在两个连续阶段：第一个阶段确定手臂将手运送到的位置，第二个阶段塑造整个上肢以抓握和操作物体。
