Hömberg V, Reiners K, Hefter H, Freund H J
Electroencephalogr Clin Neurophysiol. 1986 Mar;63(3):209-22. doi: 10.1016/0013-4694(86)90087-8.
Starting from the observation that the part above 6 Hz of the power spectrum of force tremor during isometric contractions can be related to the unfused twitches of motor units firing asynchronously, an attempt was made to study the usefulness of force tremor spectral analysis as a global descriptor of motoneurone pool activity. To compensate for the mechanical low-pass filter characteristic of skeletal muscle which leads to increased damping of mechanical ripples at higher frequencies, a numerical compensation rule was derived from data obtained by electrical microstimulation of small ensembles of motor units (MUs). Hidden line plots of consecutive partially overlapping spectra allowed visualization of changes in spectral composition during ongoing muscle activity. The resulting muscle activity spectra (MAS) showed broad peaks according to the range of onset firing rates in normal subjects. These tended to shift to higher frequencies with increasing force. Under conditions with increased synchronization of the MUs these broad peaks were replaced by sharp peaks corresponding to the burst repetition rate. Patients with different motor dysfunctions were selected to illustrate how alterations of MU activity are reflected in the MAS. Decreased or increased firing rates were observed as well as abnormal states of synchronization. It is concluded that the MAS provides useful information about some aspects of the discharge characteristics of ensembles of MUs and therefore represents a method to monitor some qualitative 'image' of the MU activities within a muscle.
基于等长收缩期间力量震颤功率谱中6赫兹以上部分可与运动单位异步发放的不完全强直收缩相关这一观察结果，人们尝试研究力量震颤频谱分析作为运动神经元池活动整体描述指标的实用性。为补偿骨骼肌的机械低通滤波特性（该特性导致高频处机械波动的阻尼增加），从对小群运动单位（MU）进行电微刺激所获数据中推导出了一个数值补偿规则。连续部分重叠频谱的隐藏线图能够呈现肌肉持续活动期间频谱组成的变化。所得的肌肉活动频谱（MAS）根据正常受试者起始发放率的范围显示出宽峰。随着力量增加，这些宽峰往往会向更高频率移动。在运动单位同步性增加的情况下，这些宽峰被对应于爆发重复率的尖峰所取代。选择患有不同运动功能障碍的患者来说明运动单位活动的改变如何在MAS中得到体现。观察到发放率降低或增加以及同步异常状态。得出的结论是，MAS提供了有关运动单位群放电特性某些方面的有用信息，因此代表了一种监测肌肉内运动单位活动某些定性“图像”的方法。
