Gorbet Diana J, Sergio Lauren E
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
Brain Res. 2009 Aug 11;1284:77-88. doi: 10.1016/j.brainres.2009.05.057. Epub 2009 Jun 2.
Many of our daily movements use visual information to guide our arms toward objects of interest. Typically, these visually guided movements involve first focusing our gaze on the intended target and then reaching toward the direction of our gaze. The literature on eye-hand coordination provides a great deal of evidence that circuitry in the brain exists which can couple eye and arm movements. Moving both of these effectors towards a common spatial direction may be a default setting used by the brain to simplify the planning of movements. We tested this idea in 20 subjects using two experimental tasks. In a "Standard" condition, the eyes and a cursor were guided to the same spatial location by moving the arm (on a touchpad) and the eyes in the same direction. In a "Dissociated" condition, the eye and cursor were again guided to the same spatial location but the arm was required to move in a direction opposite to the eyes to successfully achieve this goal. In this study, we observed that dissociating the directions of eye and arm movement significantly changed the kinematic properties of both effectors including the latency and peak velocity of eye movements and the curvature of hand-path trajectories. Thus, forcing the brain to plan simultaneous eye and arm movements in different directions alters some of the basic (and often stereotyped) characteristics of motor responses. We suggest that interference with the function of a neural network that couples gaze and reach to congruent spatial locations underlies these kinematic alterations.
我们日常的许多动作都利用视觉信息将手臂引向感兴趣的物体。通常,这些视觉引导的动作首先要将目光聚焦在目标物体上,然后朝着目光的方向伸手。关于眼手协调的文献提供了大量证据,表明大脑中存在能够将眼睛和手臂动作联系起来的神经回路。将这两种效应器朝着共同的空间方向移动,可能是大脑用来简化动作规划的一种默认设置。我们使用两项实验任务,对20名受试者进行了测试。在“标准”条件下,通过将手臂(在触摸板上)和眼睛朝同一方向移动,使眼睛和光标指向同一空间位置。在“分离”条件下,眼睛和光标同样指向同一空间位置,但手臂需要朝着与眼睛相反的方向移动才能成功实现这一目标。在这项研究中,我们观察到眼睛和手臂运动方向的分离显著改变了两种效应器的运动学特性,包括眼球运动的潜伏期和峰值速度以及手部轨迹的曲率。因此,迫使大脑计划同时进行不同方向的眼睛和手臂运动,会改变运动反应的一些基本(且通常是刻板的)特征。我们认为,对将注视和伸手动作耦合到一致空间位置的神经网络功能的干扰,是这些运动学改变的基础。