Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
J Neurophysiol. 2013 Feb;109(3):768-81. doi: 10.1152/jn.00670.2012. Epub 2012 Nov 14.
Previous studies in neurologically intact subjects have shown that motor coordination can be described by task-dependent combinations of a few muscle synergies, defined here as a fixed pattern of activation across a set of muscles. Arm function in severely impaired stroke survivors is characterized by stereotypical postural and movement patterns involving the shoulder and elbow. Accordingly, we hypothesized that muscle synergy composition is altered in severely impaired stroke survivors. Using an isometric force matching protocol, we examined the spatial activation patterns of elbow and shoulder muscles in the affected arm of 10 stroke survivors (Fugl-Meyer <25/66) and in both arms of six age-matched controls. Underlying muscle synergies were identified using non-negative matrix factorization. In both groups, muscle activation patterns could be reconstructed by combinations of a few muscle synergies (typically 4). We did not find abnormal coupling of shoulder and elbow muscles within individual muscle synergies. In stroke survivors, as in controls, two of the synergies were comprised of isolated activation of the elbow flexors and extensors. However, muscle synergies involving proximal muscles exhibited consistent alterations following stroke. Unlike controls, the anterior deltoid was coactivated with medial and posterior deltoids within the shoulder abductor/extensor synergy and the shoulder adductor/flexor synergy in stroke was dominated by activation of pectoralis major, with limited anterior deltoid activation. Recruitment of the altered shoulder muscle synergies was strongly associated with abnormal task performance. Overall, our results suggest that an impaired control of the individual deltoid heads may contribute to poststroke deficits in arm function.
先前在神经功能正常的受试者中进行的研究表明，运动协调可以通过几种肌肉协同作用的任务依赖性组合来描述，这里将其定义为一组肌肉的固定激活模式。严重受损的中风幸存者的手臂功能表现为涉及肩部和肘部的典型姿势和运动模式。因此，我们假设严重受损的中风幸存者的肌肉协同作用组成发生了改变。我们使用等长力匹配协议，检查了 10 名中风幸存者（Fugl-Meyer <25/66）受影响手臂中肘部和肩部肌肉的空间激活模式，以及 6 名年龄匹配对照者的双臂。使用非负矩阵分解来识别潜在的肌肉协同作用。在两组中，肌肉激活模式都可以通过几种肌肉协同作用（通常为 4 种）的组合来重建。我们没有发现个体肌肉协同作用中肩部和肘部肌肉的异常耦合。在中风幸存者中，与对照组一样，其中两种协同作用包括肘部屈肌和伸肌的孤立激活。然而，涉及近端肌肉的肌肉协同作用在中风后表现出一致的改变。与对照组不同，三角肌前束在肩部外展肌/伸肌协同作用和肩部内收肌/屈肌协同作用中与三角肌中束和后束共同激活，而在中风中，胸大肌的激活占主导地位，三角肌前束的激活有限。改变后的肩部肌肉协同作用的募集与异常的任务表现密切相关。总体而言，我们的研究结果表明，个体三角肌头部的控制受损可能导致中风后手臂功能的缺陷。
