Kilner J M, Alonso-Alonso M, Fisher R, Lemon R N
Sobell Department of Neurophysiology, Institute of Neurology, University College London, Queen Square, UK.
J Physiol. 2002 Jun 15;541(Pt 3):937-48. doi: 10.1113/jphysiol.2001.013305.
During precision grip, coherence between motor cortex and hand muscle EMG oscillatory activity in the 15-30 Hz range covaries with the compliance of the manipulated object. The current study investigated whether short-term synchrony and coherence between discharges of single motor units (SMUs) in the first dorsal interosseous (1DI) muscle were similarly modulated by object compliance during precision grip. Eight subjects used index finger and thumb to grip two levers that were under robotic control. Guided by visual feedback of the lever force levels, subjects held the levers against a steady force of 1.3 N for 8 s; they then linearly increased the force to 1.6 N over a 2 s period and held for a further 8 s before linearly decreasing the force back to the 1.3 N level over another 2 s period. Subjects performed the task at two different levels of compliance, each with identical grip force levels. Both surface EMG and SMU activity were recorded from the 1DI muscle. Short-term synchrony between the discharges of pairs of SMUs was assessed in the time domain by cross-correlation and in the frequency domain by coherence analysis. Coherence was seen in two frequency ranges: 6-12 Hz and 15-30 Hz. The compliance of the gripped object had a significant effect on both short-term synchronisation and coherence in the 15-30 Hz range between SMUs; both were greater for the more compliant condition. There was no change in the 6-12 Hz coherence.
在精确抓握过程中，运动皮层与手部肌肉肌电图在15 - 30赫兹范围内的振荡活动之间的相干性会随被操作物体的顺应性而变化。本研究调查了在精确抓握过程中，第一背侧骨间肌（1DI）中单个运动单位（SMU）放电之间的短期同步性和相干性是否同样受到物体顺应性的调节。八名受试者用食指和拇指抓握两个由机器人控制的杠杆。在杠杆力水平的视觉反馈引导下，受试者以1.3牛的稳定力握住杠杆8秒；然后在2秒内将力线性增加到1.6牛，并再保持8秒，之后在另外2秒内将力线性降低回到1.3牛的水平。受试者在两种不同顺应性水平下执行任务，每种水平下抓握力水平相同。从1DI肌肉记录表面肌电图和SMU活动。通过互相关在时域中以及通过相干分析在频域中评估成对SMU放电之间的短期同步性。在两个频率范围内观察到相干性：6 - 12赫兹和15 - 30赫兹。被抓握物体的顺应性对15 - 30赫兹范围内SMU之间的短期同步性和相干性均有显著影响；在顺应性更高的情况下，两者都更大。6 - 12赫兹的相干性没有变化。
