Gritsenko V, Yakovenko S, Kalaska J F
Groupe de Recherche sur le Système Nerveux Central, Département de Physiologie, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montreal, Quebec H3C 3J7, Canada.
J Neurophysiol. 2009 Aug;102(2):914-30. doi: 10.1152/jn.91324.2008. Epub 2009 May 27.
Online control of movement requires complex integration of predictive central feedforward and peripheral sensory feedback signals. We studied the hand trajectories of human subjects pointing to visual targets that abruptly changed locations by different amounts and modeled the mechanism of rapid online correction using a dynamic model of a two-joint limb. Small unperceived and large detected target displacements could be attributed to different origins (motor execution errors vs. environmental changes, respectively) and compensated differently. However, the behavioral findings indicate that the rapid feedback pathway is recruited regardless of the amplitude or subjective awareness of target displacement and that the size of the earliest correction is always proportional to the amplitude of the target displacement over the tested range of perturbations. The modeling findings suggest that the rapid online corrections can be accomplished by superimposing a dynamically appropriate error correction signal onto the outgoing feedforward motor command to the original target. Furthermore, the modeling shows that the online correction mechanism must include compensation for the dynamic mechanical properties of the limb and for sensory delays in its error-correction pathway.
在线运动控制需要对预测性中枢前馈和外周感觉反馈信号进行复杂整合。我们研究了人类受试者指向视觉目标的手部轨迹，这些目标的位置会突然发生不同程度的变化，并使用双关节肢体的动态模型对快速在线校正机制进行建模。小的未被察觉的和大的可检测到的目标位移可能分别归因于不同的起源（运动执行误差与环境变化），并且补偿方式也不同。然而，行为学研究结果表明，无论目标位移的幅度或主观意识如何，快速反馈通路都会被激活，并且在测试的扰动范围内，最早校正的大小始终与目标位移的幅度成正比。建模研究结果表明，快速在线校正可以通过将动态适当的误差校正信号叠加到发送给原始目标的前馈运动指令上来实现。此外，建模表明，在线校正机制必须包括对肢体动态机械特性以及其误差校正通路中的感觉延迟的补偿。
