Saijo Naoki, Murakami Ikuya, Nishida Shin'ya, Gomi Hiroaki
NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Kanagawa 243-0198, Japan.
J Neurosci. 2005 May 18;25(20):4941-51. doi: 10.1523/JNEUROSCI.4143-04.2005.
Recent neuroscience studies have been concerned with how aimed movements are generated on the basis of target localization. However, visual information from the surroundings as well as from the target can influence arm motor control, in a manner similar to known effects in postural and ocular motor control. Here, we show an ultra-fast manual motor response directly induced by a large-field visual motion. This rapid response aided reaction when the subject moved his hand in the direction of visual motion, suggesting assistive visually evoked manual control during postural movement. The latency of muscle activity generating this response was as short as that of the ocular following responses to the visual motion. Abrupt visual motion entrained arm movement without affecting perceptual target localization, and the degrees of motion coherence and speed of the visual stimulus modulated this arm response. This visuomotor behavior was still observed when the visual motion was confined to the "follow-through" phase of a hitting movement, in which no target existed. An analysis of the arm movements suggests that the hitting follow through made by the subject is not a part of a reaching movement. Moreover, the arm response was systematically modulated by hand bias forces, suggesting that it results from a reflexive control mechanism. We therefore propose that its mechanism is radically distinct from motor control for aimed movements to a target. Rather, in an analogy with reflexive eye movement stabilizing a retinal image, we consider that this mechanism regulates arm movements in parallel with voluntary motor control.
最近的神经科学研究关注的是有目标的动作如何基于目标定位而产生。然而，来自周围环境以及目标的视觉信息能够以类似于姿势和眼球运动控制中已知效应的方式影响手臂运动控制。在此，我们展示了一种由大视野视觉运动直接诱发的超快速手动运动反应。当受试者朝着视觉运动方向移动手部时，这种快速反应有助于反应，表明在姿势运动过程中存在辅助性视觉诱发的手动控制。产生这种反应的肌肉活动潜伏期与眼球对视觉运动的跟随反应潜伏期一样短。突然的视觉运动带动手臂运动，而不影响对目标的感知定位，并且视觉刺激的运动连贯性程度和速度调节了这种手臂反应。当视觉运动局限于击打动作的“随挥”阶段（此时不存在目标）时，这种视觉运动行为仍然可以观察到。对手臂运动的分析表明，受试者做出的击打随挥动作并非伸手动作的一部分。此外，手臂反应受到手部偏向力的系统性调节，这表明它源于一种反射控制机制。因此，我们提出其机制与针对目标的有目标动作的运动控制截然不同。相反，类似于稳定视网膜图像的反射性眼球运动，我们认为这种机制与自主运动控制并行调节手臂运动。
