Neuromotor Noise Is Malleable by Amplifying Perceived Errors

Variability in motor performance results from the interplay of error correction and neuromotor noise. This study examined whether visual amplification of error, previously shown to improve performance, affects not only error correction, but also neuromotor noise, typically regarded as inaccessible to intervention. Seven groups of healthy individuals, with six participants in each group, practiced a virtual throwing task for three days until reaching a performance plateau. Over three more days of practice, six of the groups received different magnitudes of visual error amplification; three of these groups also had noise added. An additional control group was not subjected to any manipulations for all six practice days. The results showed that the control group did not improve further after the first three practice days, but the error amplification groups continued to decrease their error under the manipulations. Analysis of the temporal structure of participants’ corrective actions based on stochastic learning models revealed that these performance gains were attained by reducing neuromotor noise and, to a considerably lesser degree, by increasing the size of corrective actions. Based on these results, error amplification presents a promising intervention to improve motor function by decreasing neuromotor noise after performance has reached an asymptote. These results are relevant for patients with neurological disorders and the elderly. More fundamentally, these results suggest that neuromotor noise may be accessible to practice interventions.运动表现的变异性源于误差校正与神经运动噪声（neuromotor noise）的动态交互作用。本研究旨在探究此前被证实可提升运动表现的视觉误差放大（visual amplification of error）手段，是否不仅会作用于误差校正过程，还会对通常被认为无法通过干预手段调控的神经运动噪声产生影响。本研究共招募7组健康受试者，每组包含6名参与者，要求其连续3天完成虚拟投掷任务（virtual throwing task）练习，直至运动表现达到平台期。在后续3天的练习阶段，其中6组受试者接受了不同幅度的视觉误差放大干预，且其中3组额外叠加了噪声干扰。另有1个对照组在全部6天的练习周期内未接受任何实验操控。实验结果显示，对照组在最初3天练习结束后，运动表现未再出现显著提升；而接受视觉误差放大干预的各组，在干预期间仍持续降低其运动误差。基于随机学习模型（stochastic learning models）对受试者校正动作的时间结构进行分析后发现，这类运动表现的提升主要通过降低神经运动噪声实现，仅在极小程度上通过增大校正动作的幅度达成。基于上述结果，视觉误差放大手段可作为一种颇具前景的干预方案，在运动表现达到渐近线后，通过降低神经运动噪声来改善运动功能。该研究结果对神经系统疾病（neurological disorders）患者与老年群体具有重要参考价值。更具根本性的意义在于，本研究表明神经运动噪声或可通过练习类干预手段进行调控。