Merging of Healthy Motor Modules Predicts Reduced Locomotor Performance and Muscle Coordination Complexity Post-Stroke
Merging of Healthy Motor Modules Predicts Reduced Locomotor Performance and Muscle Coordination Complexity Post-Stroke
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DOI：
10.1152/jn.00825.2009
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发表时间：
2010-02-01
影响因子：
2.5
通讯作者：
Kautz, Steven A.
中科院分区：
文献类型：
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作者：
Clark, David J.;Ting, Lena H.;Kautz, Steven A.
克拉克 DJ、Ting LH、Zajac FE、Neptune RR、Kautz SA。健康运动模块的合并预示着中风后运动性能和肌肉协调复杂性的降低。 J Neurophysiol 103: 844-857, 2010。首次发表于 2009 年 12 月 9 日； doi：10.1152/jn.00825.2009。有证据表明，神经系统使用肌肉激活的低维模块化组织来控制运动任务。然而，尚不清楚这种组织是否适用于人类行走的协调，也不清楚神经系统损伤如何改变运动模块的组织及其生物力学输出。我们首先测试了这样的假设：步行过程中的肌肉激活模式是通过一小组运动模块的可变激活产生的。在 20 名健康对照受试者中，在一系列步行速度下测量了八块腿部肌肉的肌电图信号。通过非负矩阵分解确定的四个运动模块足以解释肌肉激活在步与步之间以及不同速度之间的变化。接下来，与中风后肢体屈伸协同作用异常的临床概念一致，我们测试了这样的假设：中风后偏瘫受试者会改变运动模块，导致行走能力受损。在中风后受试者（n = 55）中，显示出不太复杂的协调模式。与对照组相比，以首选速度行走时需要更少的模块来解释肌肉激活。在健康对照中观察到的模块合并导致模块减少，表明神经控制信号的独立性降低。模块的数量与首选步行速度、速度调节、步长不对称性和推进不对称性相关。我们的结果表明，健康人和中风后受试者的行走都有共同的肌肉协调模块化组织。运动模块的识别可能会带来对运动协调受损和潜在神经系统的新见解。
Clark DJ, Ting LH, Zajac FE, Neptune RR, Kautz SA. Merging of healthy motor modules predicts reduced locomotor performance and muscle coordination complexity post-stroke. J Neurophysiol 103: 844-857, 2010. First published December 9, 2009; doi: 10.1152/jn.00825.2009. Evidence suggests that the nervous system controls motor tasks using a low-dimensional modular organization of muscle activation. However, it is not clear if such an organization applies to coordination of human walking, nor how nervous system injury may alter the organization of motor modules and their biomechanical outputs. We first tested the hypothesis that muscle activation patterns during walking are produced through the variable activation of a small set of motor modules. In 20 healthy control subjects, EMG signals from eight leg muscles were measured across a range of walking speeds. Four motor modules identified through nonnegative matrix factorization were sufficient to account for variability of muscle activation from step to step and across speeds. Next, consistent with the clinical notion of abnormal limb flexion-extension synergies post-stroke, we tested the hypothesis that subjects with post-stroke hemiparesis would have altered motor modules, leading to impaired walking performance. In post-stroke subjects (n = 55), a less complex coordination pattern was shown. Fewer modules were needed to account for muscle activation during walking at preferred speed compared with controls. Fewer modules resulted from merging of the modules observed in healthy controls, suggesting reduced independence of neural control signals. The number of modules was correlated to preferred walking speed, speed modulation, step length asymmetry, and propulsive asymmetry. Our results suggest a common modular organization of muscle coordination underlying walking in both healthy and post-stroke subjects. Identification of motor modules may lead to new insight into impaired locomotor coordination and the underlying neural systems.