Coordination between digit forces and positions: interactions between anticipatory and feedback control
Coordination between digit forces and positions: interactions between anticipatory and feedback control
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DOI：
10.1152/jn.00754.2013
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发表时间：
2014-04-01
影响因子：
2.5
通讯作者：
Santello, Marco
中科院分区：
文献类型：
--
作者：
Fu, Qiushi;Santello, Marco
人类调整手指的力量，以弥补试验到试验的变化，在手指的位置在对象操作，但基本的控制机制仍有待确定。我们假设这种手指位置/力的协调是通过视觉引导的前馈规划和基于触觉的反馈控制来实现的。问题是这两种机制之间相互作用的时间进程。使用虚拟现实环境和触觉设备，通过受试者在虚拟对象上产生扭矩（+/-70N中心点mm）来控制光标移动到目标位置以抓住下落的球的任务来测试这一点。虚拟对象的宽度在大（L）和小（S）之间变化。这些物体宽度导致显著不同的水平手指相对位置，并且需要不同的手指力来施加相同的任务扭矩。训练后，受试者进行了测试与随机序列的L和S宽度有或没有视觉信息的对象的宽度。我们发现，视觉线索允许受试者计划接触前的操纵力。相比之下，当视觉线索无法预测数字的位置，受试者实施了一个“默认”的数字力计划，数字接触后，最终完成任务。手指力量的时间过程表明，在没有视觉线索的情况下，力量的发展被延迟。具体而言，适当的手指力调整后250 - 300毫秒的初始对象接触。这一结果支持了我们的假设，并进一步揭示了触觉反馈本身就足以实现手指力-位置协调。
Humans adjust digit forces to compensate for trial-to-trial variability in digit placement during object manipulation, but the underlying control mechanisms remain to be determined. We hypothesized that such digit position/ force coordination was achieved by both visually guided feed-forward planning and haptic-based feedback control. The question arises about the time course of the interaction between these two mechanisms. This was tested with a task in which subjects generated torque (+/- 70 N center dot mm) on a virtual object to control a cursor moving to target positions to catch a falling ball, using a virtual reality environment and haptic devices. The width of the virtual object was varied between large (L) and small (S). These object widths result in significantly different horizontal digit relative positions and require different digit forces to exert the same task torque. After training, subjects were tested with random sequences of L and S widths with or without visual information about object width. We found that visual cues allowed subjects to plan manipulation forces before contact. In contrast, when visual cues were not available to predict digit positions, subjects implemented a "default" digit force plan that was corrected after digit contact to eventually accomplish the task. The time course of digit forces revealed that force development was delayed in the absence of visual cues. Specifically, the appropriate digit force adjustments were made 250300 ms after initial object contact. This result supports our hypothesis and further reveals that haptic feedback alone is sufficient to implement digit force-position coordination.