Brown P, Salenius S, Rothwell J C, Hari R
Medical Research Council Human Movement and Balance Unit, Institute of Neurology, London WC1 3BG, United Kingdom.
J Neurophysiol. 1998 Dec;80(6):2911-7. doi: 10.1152/jn.1998.80.6.2911.
Cortical correlate of the Piper rhythm in humans. J. Neurophysiol. 80: 2911-2917, 1998. The electromyogram (EMG) of healthy humans demonstrates a tendency to rhythmic oscillations at around 40 Hz (the Piper rhythm) during strong voluntary contraction. Why motor units should discharge synchronously locked to such a high-frequency is unclear. We recorded whole scalp magnetoencephalographic (MEG) signals simultaneously with surface EMG from 10 healthy subjects. In eight subjects, coherence and time domain analyses demonstrated correspondence between the MEG signal, originating near or in the hand region of the motor cortex, and the 35- to 60-Hz EMG recorded during repeated maximal isometric contractions of the contralateral forearm extensor muscles. Three of these subjects also showed similar coherence during isometric contractions of moderate strength and slow extension movements of the wrist. In addition, coherence and time domain analyses demonstrated correspondence between the MEG signals originating near or in the foot area of the motor cortex and EMG recorded during repeated maximal isometric contractions of the contralateral tibialis anterior muscle in the 30- to 60-Hz range. Most important, the frequency at the peak of the coherence spectrum differed between forearm and leg by as much as 10 Hz in the same subject. In contrast, the peak of the coherence spectrum occurred during sustained weak contraction in the 20- to 30-Hz range similarly for both forearm and foot. The lag between EMG and MEG activity in the leg was approximately 15 ms greater than that seen in the forearm, an interval appropriate for conduction in fast pyramidal pathways. It is concluded that the Piper rhythm in muscle may be driven by a comparable oscillatory activity in the contralateral motor cortex. This cortical rhythmicity can be picked up in several types of movement and seems distinct from the 20- to 30-Hz rhythmicity recorded during weak sustained contractions.
人类Piper节律的皮层关联。《神经生理学杂志》80: 2911 - 2917, 1998年。健康人的肌电图（EMG）显示，在强烈的自主收缩过程中，有在约40赫兹（Piper节律）附近出现节律性振荡的趋势。运动单位为何会同步锁定在这样一个高频仍不清楚。我们同时记录了10名健康受试者的全头皮脑磁图（MEG）信号和表面肌电图。在8名受试者中，相干性和时域分析表明，起源于运动皮层手部区域附近或内部的MEG信号与对侧前臂伸肌重复最大等长收缩期间记录的35至60赫兹肌电图之间存在对应关系。其中3名受试者在中等强度等长收缩和手腕缓慢伸展运动期间也表现出类似的相干性。此外，相干性和时域分析表明，起源于运动皮层足部区域附近或内部的MEG信号与对侧胫骨前肌重复最大等长收缩期间记录的30至60赫兹肌电图之间存在对应关系。最重要的是，在同一受试者中，前臂和腿部相干谱峰值处的频率相差多达10赫兹。相比之下，前臂和足部在持续弱收缩期间，相干谱峰值出现在20至30赫兹范围内的情况类似。腿部肌电图和MEG活动之间的延迟比前臂大约15毫秒，这一间隔适合快速锥体束传导。结论是，肌肉中的Piper节律可能由对侧运动皮层中类似的振荡活动驱动。这种皮层节律性可以在几种类型的运动中检测到，并且似乎与弱持续收缩期间记录的20至30赫兹节律性不同。
