Jacobs J V, Wu G, Kelly K M
Department of Rehabilitation and Movement Science, University of Vermont, 305 Rowell Building, 106 Carrigan Drive, Burlington, VT 05405, USA.
Neuroscience. 2015 Jul 9;298:1-11. doi: 10.1016/j.neuroscience.2015.04.009. Epub 2015 Apr 11.
The role of the cerebral cortex in maintaining human standing balance remains unclear. Beta corticomuscular coherence (CMC) provides a measure of communication between the sensory-motor cortex and muscle, but past literature has not demonstrated significant beta CMC during human stance. This study evaluated the effects of stance width, vision, and surface compliance on beta CMC during human stance using methods to enhance sensitivity to CMC. Ten healthy, young adults stood for three 60-s trials in each of a wide or narrow stance width while on a firm surface and in narrow stance on a foam surface, each with eyes open or closed. Beta CMC was calculated between contralateral electroencephalographic and electromyographic recordings. Electromyography was recorded from bilateral tibialis anterior and gastrocnemius lateralis muscles. CMC magnitude was defined as the average integrated area of coherence spectrum above a significance threshold. Measures of center-of-pressure (COP) sway were derived from force plates under the subjects' feet. Results of CMC from four muscles across six stance conditions (a total of 24 combinations) demonstrated significant average CMC magnitude from every subject in 20 combinations and significant average CMC magnitude in nine of 10 subjects in the remaining four combinations. The CMC magnitude was significantly larger in the wide-stance condition than in the narrow-stance condition with eyes open. No significant differences were detected when comparing eyes-open to eyes-closed conditions or when comparing firm- to foam-surface conditions. Correlations between CMC magnitude and COP sway elicited some significant relationships, but there was no consistent direction or pattern of correlation based on muscle or stance condition. Results demonstrate that significant beta CMC is evident during human standing balance, and that beta CMC is responsive to changes in mechanical, but not visual or surface, conditions.
大脑皮层在维持人体站立平衡中的作用仍不清楚。β皮质肌相干性（CMC）提供了一种衡量感觉运动皮层与肌肉之间通信的指标，但过去的文献尚未证明在人体站立时存在显著的β CMC。本研究使用增强对CMC敏感性的方法，评估了站立宽度、视觉和表面顺应性对人体站立时β CMC的影响。10名健康的年轻成年人在坚硬表面上分别以宽或窄的站立宽度站立3次，每次60秒，以及在泡沫表面上以窄站立宽度站立，每次均睁眼或闭眼。对侧脑电图和肌电图记录之间计算β CMC。从双侧胫前肌和外侧腓肠肌记录肌电图。CMC幅度定义为相干谱高于显著性阈值的平均积分面积。压力中心（COP）摆动的测量值来自受试者脚下的测力板。来自六种站立条件（共24种组合）下四块肌肉的CMC结果表明，在20种组合中每个受试者的平均CMC幅度均显著，在其余四种组合中10名受试者中有9名的平均CMC幅度显著。睁眼时宽站立条件下的CMC幅度显著大于窄站立条件。睁眼与闭眼条件比较或坚硬表面与泡沫表面条件比较时未检测到显著差异。CMC幅度与COP摆动之间的相关性产生了一些显著关系，但基于肌肉或站立条件没有一致的相关方向或模式。结果表明，在人体站立平衡期间显著的β CMC是明显的，并且β CMC对机械条件的变化有反应，但对视觉或表面条件没有反应。
