Flexible, task-dependent use of sensory feedback to control hand movements.
Flexible, task-dependent use of sensory feedback to control hand movements.
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DOI：
10.1523/jneurosci.3522-09.2011
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发表时间：
2011-01-26
期刊：
影响因子：
--
通讯作者：
Chhabra M
中科院分区：
文献类型：
--
作者：
Knill DC;Bondada A;Chhabra M
我们测试了改变对简单指点动作的准确性要求是否会导致人类调整反馈控制规律，这些反馈控制规律将感觉信号从移动的手映射到运动指令。受试者在虚拟环境中进行重复的指点动作，以触摸一个按钮，该按钮的形状随试验的不同而随机变化--方块、垂直于移动路径的矩形和平行于移动路径的矩形。受试者在水平桌子上完成这项任务，但通过安装在显示器和桌子之间的镜子看到目标配置和手指的虚拟渲染。在三分之一的试验中，当虚拟手指穿过封堵器后时，虚拟手指的位置在移动方向上或垂直于移动方向时受到±1厘米的扰动。尽管受试者没有有意识地注意到干扰，但他们很快就纠正了这些干扰；然而，他们对与目标的狭窄维度一致的干扰的纠正几乎是对与长维度一致的干扰的纠正的两倍。这些表观反馈增益的变化出现在摄动后不久的运动学轨迹中，表明它们反映了在整个运动持续时间内使用的反馈控制律的不同。结果表明，大脑“按需”调整其反馈控制律，以适应任务需求。对两关节臂的最优控制律的仿真表明，仅精度要求和信号相关噪声导致的行为本质上是相同的。
We tested whether changing accuracy demands for simple pointing movements leads humans to adjust the feedback control laws that map sensory signals from the moving hand to motor commands. Subjects made repeated pointing movements in a virtual environment to touch a button whose shape varied randomly from trial-to-trial – between squares, rectangles oriented perpendicular to the movement path and rectangles oriented parallel to the movement path. Subjects performed the task on a horizontal table, but saw the target configuration and a virtual rendering of their pointing finger through a mirror mounted between a monitor and the table. On a one-third of trials, the position of the virtual finger was perturbed by ±1 cm either in the movement direction or perpendicular to the movement direction when the finger passed behind an occluder. Subjects corrected quickly for the perturbations despite not consciously noticing them; however, they corrected almost twice as much for perturbations aligned with the narrow dimension of a target than for perturbations aligned with the long dimension. These changes in apparent feedback gain appeared in the kinematic trajectories soon after the time of the perturbations, indicating that they reflect differences in the feedback control law used throughout the duration of movements. The results indicate that the brain adjusts its feedback control law for individual movements “on-demand” to fit task demands. Simulations of optimal control laws for a two-joint arm show that accuracy demands alone, coupled with signal dependent noise lead to qualitatively the same behavior.