Wang Shouyan, Aziz Tipu Z, Stein John F, Bain Peter G, Liu Xuguang
Department of Physiology, Anatomy, and Genetics, University of Oxford, and Department of Neurosurgery, Radcliffe Infirmary, Woodstock Road, Oxford OX2 6HE, UK.
Clin Neurophysiol. 2006 Jul;117(7):1487-98. doi: 10.1016/j.clinph.2006.03.027. Epub 2006 Jun 5.
To differentiate physiological from harmonic components in coherence analysis of the tremor-related neural and muscular signals by comparing power, cross-power and coherence spectra.
Influences of waveform, burst-width and additional noise on generating harmonic peaks in the power, cross-power and coherence spectra were studied using simulated signals. The local field potentials (LFPs) of the subthalamic nucleus (STN) and the EMGs of the contralateral forearm muscles in PD patients with rest tremor were analysed.
(1) Waveform had significant effect on generating harmonics; (2) noise significantly decreased the coherence values in a frequency-dependent fashion; and (3) cross-spectrum showed high resistance to harmonics. Among six examples of paired LFP-EMG signals, significant coherence appeared at the tremor frequency only, both the tremor and double tremor frequencies and the double-tremor frequency only.
In coherence analysis of neural and muscular signals, distortion in waveform generates significant harmonic peaks in the coherence spectra and the coherence values of both physiological and harmonic components are modulated by extra noise or non-tremor related activity.
The physiological or harmonic nature of a coherence peak at the double tremor frequency may be differentiated when the coherence spectra are compared with the power and in particular the cross-power spectra.
通过比较功率谱、互功率谱和相干谱，区分震颤相关神经和肌肉信号相干分析中的生理成分与谐波成分。
使用模拟信号研究波形、脉冲宽度和附加噪声对功率谱、互功率谱和相干谱中谐波峰值产生的影响。分析了伴有静止性震颤的帕金森病患者丘脑底核（STN）的局部场电位（LFP）和对侧前臂肌肉的肌电图（EMG）。
（1）波形对谐波的产生有显著影响；（2）噪声以频率依赖的方式显著降低相干值；（3）互谱对谐波具有高抗性。在六对LFP-EMG信号示例中，显著相干仅出现在震颤频率处、震颤频率和双震颤频率处以及仅双震颤频率处。
在神经和肌肉信号的相干分析中，波形失真会在相干谱中产生显著的谐波峰值，并且生理成分和谐波成分的相干值都会受到额外噪声或非震颤相关活动的调制。
当将相干谱与功率谱特别是互功率谱进行比较时，双震颤频率处相干峰的生理或谐波性质可以得到区分。
