Gribble Paul L, Everling Stefan, Ford Kristen, Mattar Andrew
Department of Physiology, The University of Western Ontario, London, Ontario N6A 5C2, Canada.
Exp Brain Res. 2002 Aug;145(3):372-82. doi: 10.1007/s00221-002-1122-9. Epub 2002 Jun 14.
Visually guided arm movements such as reaching or pointing are accompanied by saccadic eye movements that typically begin prior to motion of the arm. In the past, some degree of coupling between the oculomotor and limb motor systems has been demonstrated by assessing the relative onset times of eye and arm movement, and by the demonstration of a gap effect for arm movement reaction times. However, measures of limb movement onset time based on kinematics are affected by factors such as the relatively high inertia of the limb and neuromechanical delays. The goal of the present study was thus to assess the relative timing of rapid eye and arm movements made to visual targets by examining electromyographic (EMG) activity of limb muscles in conjunction with eye and arm position measures. The observation of a positive correlation between eye and limb EMG onset latencies, and the presence of a gap effect for limb EMG onset times (a reduction in reaction time when a temporal gap is introduced between the disappearance of a central fixation point and the appearance of a new target) both support the idea that eye and arm movement initiation are linked. However, limb EMG onset in most cases precedes saccade onset, and the magnitude of EMG activity prior to eye movement is correlated with both the direction and amplitude of the upcoming arm movement. This suggests that, for the rapid movements studied here, arm movement direction and distance are specified prior to the onset of saccades.
诸如伸手或指向等视觉引导的手臂运动伴随着扫视眼动，这种眼动通常在手臂运动之前就开始了。过去，通过评估眼动和手臂运动的相对起始时间，以及通过展示手臂运动反应时间的间隙效应，已经证明了动眼系统和肢体运动系统之间存在一定程度的耦合。然而，基于运动学的肢体运动起始时间测量会受到诸如肢体相对较大的惯性和神经机械延迟等因素的影响。因此，本研究的目的是通过结合眼位和手臂位置测量来检查肢体肌肉的肌电图（EMG）活动，以评估对视觉目标做出的快速眼动和手臂运动的相对时间。观察到眼肌电图和肢体肌电图起始潜伏期之间呈正相关，以及肢体肌电图起始时间存在间隙效应（当中央注视点消失和新目标出现之间引入时间间隙时反应时间缩短），这两者都支持眼动和手臂运动起始是相关联的这一观点。然而，在大多数情况下，肢体肌电图起始先于扫视起始，并且眼动之前的肌电图活动幅度与即将到来的手臂运动的方向和幅度都相关。这表明，对于这里研究的快速运动，手臂运动的方向和距离在扫视起始之前就已确定。
