Manifold reaching paradigm: how do we handle target redundancy?
Manifold reaching paradigm: how do we handle target redundancy?
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DOI：
10.1152/jn.01063.2010
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发表时间：
2011-10-01
影响因子：
2.5
通讯作者：
Pozzo, Thierry
中科院分区：
文献类型：
--
作者：
Berret, Bastien;Chiovetto, Enrico;Pozzo, Thierry
[10]杨文，李文，李文.流形到达范式：我们如何处理目标冗余？J Neurophysiol 106：2086-2102，2011.首次发表于2011年7月6日; doi：10.1152/jn.01063.2010.-中枢神经系统如何协调肌肉骨骼系统的许多内在自由度是运动控制中经常出现的问题。许多研究通过考虑冗余的伸展任务来解决这个问题，例如点对点的手臂运动，许多关节轨迹和肌肉激活通常与单个目标兼容。然而，存在一种不同的、外在的冗余，即目标冗余。事实上，很多时候，最终要达到的点既不是特定的，也不是唯一的。在这项研究中，我们的目标是了解中枢神经系统如何处理这样一个外在的冗余，通过考虑达到一个流形的范例，更具体地说，一个手臂指向一个长长的垂直酒吧。在这种情况下，终点不是先验定义的，因此，受试者可以自由选择杆上的任何点来成功完成任务。我们调查了受试者处理这种选择所使用的策略。我们的研究结果表明，受试者间和试验间的一致性方面提供的任务的自由。然而，受试者的行为被发现比在经典的点对点达到更多的变量。有趣的是，平均手臂轨迹的酒吧和结构的试验间的端点变化可以解释通过随机最优控制与能量/平滑预期成本和信号相关的电机噪声。我们的结论是，目标冗余首先克服运动规划过程中，然后利用运动执行过程中，随机最优反馈控制原则，这说明了如何互补的问题，目标和运动选择可以解决一次。
Berret B, Chiovetto E, Nori F, Pozzo T. Manifold reaching paradigm: how do we handle target redundancy? J Neurophysiol 106: 2086-2102, 2011. First published July 6, 2011; doi: 10.1152/jn.01063.2010.-How the central nervous system coordinates the many intrinsic degrees of freedom of the musculoskeletal system is a recurrent question in motor control. Numerous studies addressed it by considering redundant reaching tasks such as point-to-point arm movements, for which many joint trajectories and muscle activations are usually compatible with a single goal. There exists, however, a different, extrinsic kind of redundancy that is target redundancy. Many times, indeed, the final point to reach is neither specified nor unique. In this study, we aim to understand how the central nervous system tackles such an extrinsic redundancy by considering a reaching-to-a-manifold paradigm, more specifically an arm pointing to a long vertical bar. In this case, the endpoint is not defined a priori and, therefore, subjects are free to choose any point on the bar to successfully achieve the task. We investigated the strategies used by subjects to handle this presented choice. Our results indicate both intersubject and intertrial consistency with respect to the freedom provided by the task. However, the subjects' behavior is found to be more variable than during classical point-to-point reaches. Interestingly, the average arm trajectories to the bar and the structure of intertrial endpoint variations could be explained via stochastic optimal control with an energy/smoothness expected cost and signal-dependent motor noise. We conclude that target redundancy is first overcome during movement planning and then exploited during movement execution, in agreement with stochastic optimal feedback control principles, which illustrates how the complementary problems of goal and movement selection may be resolved at once.