Reschechtko Sasha, Latash Mark L
Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania.
Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
J Neurophysiol. 2017 Dec 1;118(6):3152-3164. doi: 10.1152/jn.00485.2017. Epub 2017 Sep 13.
We combined the theory of neural control of movement with referent coordinates and the uncontrolled manifold hypothesis to explore synergies stabilizing the hand action in accurate four-finger pressing tasks. In particular, we tested a hypothesis on two classes of synergies, those among the four fingers and those within a pair of control variables, stabilizing hand action under visual feedback and disappearing without visual feedback. Subjects performed four-finger total force and moment production tasks under visual feedback; the feedback was later partially or completely removed. The "inverse piano" device was used to lift and lower the fingers smoothly at the beginning and at the end of each trial. These data were used to compute pairs of hypothetical control variables. Intertrial analysis of variance within the finger force space was used to quantify multifinger synergies stabilizing both force and moment. A data permutation method was used to quantify synergies among control variables. Under visual feedback, synergies in the spaces of finger forces and hypothetical control variables were found to stabilize total force. Without visual feedback, the subjects showed a force drift to lower magnitudes and a moment drift toward pronation. This was accompanied by disappearance of the four-finger synergies and strong attenuation of the control variable synergies. The indexes of the two types of synergies correlated with each other. The findings are interpreted within the scheme with multiple levels of abundant variables. We extended the idea of hierarchical control with referent spatial coordinates for the effectors and explored two types of synergies stabilizing multifinger force production tasks. We observed synergies among finger forces and synergies between hypothetical control variables that stabilized performance under visual feedback but failed to stabilize it after visual feedback had been removed. Indexes of two types of synergies correlated with each other. The data suggest the existence of multiple mechanisms stabilizing motor actions.
我们将运动的神经控制理论与参考坐标及非受控流形假设相结合，以探索在精确的四指按压任务中稳定手部动作的协同作用。具体而言，我们测试了关于两类协同作用的假设，即四指之间的协同作用以及一对控制变量内部的协同作用，它们在视觉反馈下稳定手部动作，而在没有视觉反馈时消失。受试者在视觉反馈下执行四指总力和力矩产生任务；随后部分或完全移除反馈。在每次试验开始和结束时，使用“反向钢琴”装置平稳地抬起和放下手指。这些数据用于计算假设的控制变量对。在手指力空间内进行试验间方差分析，以量化稳定力和力矩的多手指协同作用。使用数据置换方法来量化控制变量之间的协同作用。在视觉反馈下，发现手指力空间和假设控制变量空间中的协同作用可稳定总力。没有视觉反馈时，受试者表现出力量向较低幅度漂移，力矩向旋前方向漂移。这伴随着四指协同作用的消失以及控制变量协同作用的强烈衰减。两种协同作用的指标相互关联。这些发现是在具有多个丰富变量水平的框架内进行解释的。我们扩展了针对效应器的具有参考空间坐标的分层控制概念，并探索了稳定多手指力产生任务的两种协同作用类型。我们观察到手指力之间的协同作用以及假设控制变量之间的协同作用，它们在视觉反馈下稳定了表现，但在移除视觉反馈后未能稳定表现。两种协同作用的指标相互关联。数据表明存在多种稳定运动动作的机制。
