Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, John Dalton Building, Oxford Road, Manchester M1 5GD, UK.
Exp Brain Res. 2011 Aug;213(1):99-109. doi: 10.1007/s00221-011-2782-0. Epub 2011 Jul 9.
The present study examined the effect of timing constraints and advance knowledge on eye-hand coordination strategy in a sequential pointing task. Participants were required to point at two successively appearing targets on a screen while the inter-stimulus interval (ISI) and the trial order were manipulated, such that timing constraints were high (ISI = 300 ms) or low (ISI = 450 ms) and advance knowledge of the target location was present (fixed order) or absent (random order). Analysis of eye and finger onset and completion times per segment of the sequence indicated that oculo-manual behaviour was in general characterized by eye movements preceding the finger, as well as 'gaze anchoring' (i.e. eye fixation of the first target until completion of the finger movement towards that target). Advance knowledge of future target locations lead to shorter latency times of eye and hand, and smaller eye-hand lead times, which in combination resulted in shorter total movement times. There was, however, no effect of advance knowledge on the duration of gaze anchoring. In contrast, gaze anchoring did change as a function of the interval between successive stimuli and was shorter with a 300 ms ISI versus 450 ms ISI. Further correlation analysis provided some indication that shorter residual latency is associated with shorter pointing duration, without affecting accuracy. These results are consistent with a neural mechanism governing the coupling of eye and arm movements, which has been suggested to reside in the superior colliculus. The temporal coordination resulting from this coupling is a function of the time pressure on the visuo-manual system resulting from the appearance of external stimuli.
本研究考察了时间限制和提前知识对顺序指向任务中眼手协调策略的影响。参与者被要求在屏幕上指向两个相继出现的目标，同时操纵刺激间间隔（ISI）和试验顺序，使得时间限制较高（ISI=300ms）或较低（ISI=450ms），并且提前知道目标位置（固定顺序）或不知道（随机顺序）。对序列中每个片段的眼动和手指起始及完成时间的分析表明，眼手行为通常以眼球运动先于手指运动为特征，以及“注视锚定”（即第一个目标的眼睛注视固定，直到手指朝着该目标移动完成）。对未来目标位置的提前知识导致眼动和手动的潜伏期更短，眼手的启动时间更短，这两者共同导致总运动时间更短。然而，提前知识对注视锚定的持续时间没有影响。相反，注视锚定确实随着连续刺激之间的间隔而变化，ISI 为 300ms 时比 ISI 为 450ms 时更短。进一步的相关分析表明，较短的剩余潜伏期与较短的指向持续时间相关，而不影响准确性。这些结果与控制眼动和手臂运动耦合的神经机制一致，该机制被认为存在于上丘。这种耦合产生的时间协调是外部刺激出现对视觉-手动系统的时间压力的函数。
