Adjustments of Motor Pattern for Load Compensation Via Modulated Activations of Muscle Synergies During Natural Behaviors
Adjustments of Motor Pattern for Load Compensation Via Modulated Activations of Muscle Synergies During Natural Behaviors
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DOI：
10.1152/jn.01387.2007
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发表时间：
2009-03-01
影响因子：
2.5
通讯作者：
Bizzi, Emilio
中科院分区：
文献类型：
--
作者：
Cheung, Vincent C. K.;d'Avella, Andrea;Bizzi, Emilio
在自然行为中，通过调节肌肉协同作用的激活来调整运动模式以进行负荷补偿。神经生理学杂志101：1235-1257,2009。2008年12月17日首次出版；DOI：10.1152/jn.01387.2007。有人提出，运动系统可以通过结合离散的肌肉协同作用来产生运动输出，从而绕过控制肌肉骨骼装置中许多自由度的困难。一个分散组织的马达系统如何补偿不同的扰动仍然令人费解。在这里，我们研究了在惯性负载扰动后观察到的运动反应是否可以通过改变通常用于构建不受干扰的运动的协同效应的招募来产生。肌电(EMG，13块肌肉)数据从牛蛙后肢的自然行为中采集，在同一肢体被附加到小腿上的重量负荷之前、期间和之后。运动学分析显示，负荷去除没有后遗症，这表明负荷相关的肌电变化是即时运动模式调整的结果。然后，我们使用非负矩阵分解算法从肌电中提取协同效应，并开发了一种评估不同负载条件下协同效应共享程度的程序。大多数提取的协同作用被发现在所有加载和卸载条件下都被激活。然而，对于某些协同作用，它们的激活脉冲的幅度、持续时间和/或起始时间在负荷过程中被上调或下调。行为参数显示，协同激活的负荷相关调节依赖于行为的变化(例如，踢的方向和幅度)和执行的运动阶段。我们的结果表明，肌肉的协同作用在不同的动态条件下是稳健的，即时的运动调节可以通过调节协同作用的激活来完成。附录描述了我们开发的新程序，有助于从多个数据集中发现共享和特定的特征。
Cheung VCK, d'Avella A, Bizzi E. Adjustments of motor pattern for load compensation via modulated activations of muscle synergies during natural behaviors. J Neurophysiol 101: 1235-1257, 2009. First published December 17, 2008; doi:10.1152/jn.01387.2007. It has been suggested that the motor system may circumvent the difficulty of controlling many degrees of freedom in the musculoskeletal apparatus by generating motor outputs through a combination of discrete muscle synergies. How a discretely organized motor system compensates for diverse perturbations has remained elusive. Here, we investigate whether motor responses observed after an inertial-load perturbation can be generated by altering the recruitment of synergies normally used for constructing unperturbed movements. Electromyographic (EMG, 13 muscles) data were collected from the bullfrog hindlimb during natural behaviors before, during, and after the same limb was loaded by a weight attached to the calf. Kinematic analysis reveals the absence of aftereffect on load removal, suggesting that load-related EMG changes were results of immediate motor pattern adjustments. We then extracted synergies from EMGs using the nonnegative matrix factorization algorithm and developed a procedure for assessing the extent of synergy sharing across different loading conditions. Most synergies extracted were found to be activated in all loaded and unloaded conditions. However, for certain synergies, the amplitude, duration, and/or onset time of their activation bursts were up- or down-modulated during loading. Behavioral parameterizations reveal that load-related modulation of synergy activations depended on the behavioral variety (e.g., kick direction and amplitude) and the movement phase performed. Our results suggest that muscle synergies are robust across different dynamic conditions and immediate motor adjustments can be accomplished by modulating synergy activations. An appendix describes the novel procedure we developed, useful for discovering shared and specific features from multiple data sets.