Laboratory of Neurophysiology and Movement Biomechanics, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.
Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland; Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
Neuroimage. 2022 Nov 1;261:119491. doi: 10.1016/j.neuroimage.2022.119491. Epub 2022 Jul 28.
As humans, we seamlessly hold objects in our hands, and may even lose consciousness of these objects. This phenomenon raises the unsettled question of the involvement of the cerebral cortex, the core area for voluntary motor control, in dynamically maintaining steady muscle force. To address this issue, we measured magnetoencephalographic brain activity from healthy adults who maintained a steady pinch grip. Using a novel analysis approach, we uncovered fine-grained temporal modulations in the beta sensorimotor brain rhythm and its coupling with muscle activity, with respect to several aspects of muscle force (rate of increase/decrease or plateauing high/low). These modulations preceded changes in force features by ∼40 ms and possessed behavioral relevance, as less salient or absent modulation predicted a more stable force output. These findings have consequences for the existing theories regarding the functional role of cortico-muscular coupling, and suggest that steady muscle contractions are characterized by a stable rather than fluttering involvement of the sensorimotor cortex.
作为人类，我们可以毫不费力地用手握住物体，甚至可能意识不到这些物体的存在。这种现象引发了一个悬而未决的问题，即大脑皮层（自愿运动控制的核心区域）是否参与了动态维持稳定肌肉力量。为了解决这个问题，我们测量了健康成年人在保持稳定捏握时的脑磁图（MEG）脑活动。使用一种新的分析方法，我们揭示了β感觉运动脑节律及其与肌肉活动的精细时间调制，涉及肌肉力量的几个方面（增加/减少的速率或高原高/低）。这些调制比力特征的变化早约 40 毫秒，并且具有行为相关性，因为不明显或不存在的调制预示着更稳定的力输出。这些发现对现有的关于皮质-肌肉耦合的功能作用的理论产生了影响，并表明稳定的肌肉收缩的特征是感觉运动皮层的稳定参与，而不是颤动参与。
