Priot Anne-Emmanuelle, Revol Patrice, Sillan Olivier, Prablanc Claude, Gaveau Valérie
Department of Neurosciences and Cognitive Sciences, Perception Team, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.
Lyon Neuroscience Research Center, ImpAct/Trajectoires Team, Bron, France.
Front Hum Neurosci. 2020 Oct 7;14:549537. doi: 10.3389/fnhum.2020.549537. eCollection 2020.
Fast, online control of movement is an essential component of human motor skills, as it allows automatic correction of inaccurate planning. The present study explores the role of two types of concurrent signals in error correction: predicted visual reafferences coming from an internal representation of the hand, and actual visual feedback from the hand. While the role of sensory feedback in these corrections is well-established, much less is known about sensory prediction. The relative contributions of these two types of signals remain a subject of debate, as they are naturally interconnected. We address the issue in a study that compares online correction of an artificially induced, undetected planning error. Two conditions are tested, which only differ with respect to the accuracy of predicted visual reafferences. In the first, "Prism" experiment, a planning error is introduced by prisms that laterally displace the seen hand prior to hand movement onset. The prism-induced conflict between visual and proprioceptive inputs of the hand also generates an erroneous prediction of visual reafferences of the moving hand. In the second, "Jump" experiment, a planning error is introduced by a jump in the target position, during the orienting saccade, prior to hand movement onset. In the latter condition, predicted reafferences of the hand remained intact. In both experiments, after hand movement onset, the hand was either visible or hidden, which enabled us to manipulate the presence (or absence) of visual feedback during movement execution. The Prism experiment highlighted late and reduced correction of the planning error, even when natural visual feedback of the moving hand was available. In the Jump experiment, early and automatic corrections of the planning error were observed, even in the absence of visual feedback from the moving hand. Therefore, when predicted reafferences were accurate (the Jump experiment), visual feedback was processed rapidly and automatically. When they were erroneous (the Prism experiment), the same visual feedback was less efficient, and required voluntary, and late, control. Our study clearly demonstrates that in natural environments, reliable prediction is critical in the preprocessing of visual feedback, for fast and accurate movement.
快速的在线运动控制是人类运动技能的一个重要组成部分，因为它能对手部运动不准确的规划进行自动纠正。本研究探讨了两种并发信号在错误纠正中的作用：来自手部内部表征的预测视觉再传入信号，以及来自手部的实际视觉反馈。虽然感觉反馈在这些纠正中的作用已得到充分证实，但对于感觉预测却知之甚少。由于这两种信号自然相互关联，它们的相对贡献仍然是一个有争议的话题。我们在一项研究中解决了这个问题，该研究比较了对人为诱导的、未被察觉的规划错误的在线纠正。测试了两种条件，它们仅在预测视觉再传入信号的准确性方面有所不同。在第一个“棱镜”实验中，棱镜在手部运动开始前横向移动所看到的手部，从而引入规划错误。棱镜引起的手部视觉和本体感觉输入之间的冲突也会产生对手部运动视觉再传入信号的错误预测。在第二个“跳跃”实验中，在手部运动开始前的定向扫视期间，目标位置的跳跃引入了规划错误。在后一种情况下，手部的预测再传入信号保持完整。在两个实验中，手部运动开始后，手部要么可见要么隐藏，这使我们能够在运动执行过程中操纵视觉反馈的存在（或不存在）。棱镜实验突出了规划错误的后期纠正且纠正程度降低，即使在有运动手部的自然视觉反馈时也是如此。在跳跃实验中，即使没有运动手部的视觉反馈，也观察到了规划错误的早期自动纠正。因此，当预测再传入信号准确时（跳跃实验），视觉反馈能快速自动地被处理。当它们错误时（棱镜实验），相同的视觉反馈效率较低，需要有意识的后期控制。我们的研究清楚地表明，在自然环境中，可靠的预测对于视觉反馈的预处理以实现快速准确的运动至关重要。
