Physiological and harmonic components in neuromuscular coherence in Parkinsonian tremor

Wang, Shouyan, Aziz, Tipu Z., Stein, John F., Bain, Peter G. and Liu, Xuguang (2006) Physiological and harmonic components in neuromuscular coherence in Parkinsonian tremor. Clinical Neurophysiology, 117, (7), 1487-1498. (doi:10.1016/j.clinph.2006.03.027).


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Objective: 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.

Methods: 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 of the subthalamic nucleus (STN) and the EMGs of the contralateral forearm muscles in PD patients with rest tremor were analysed.

Results: (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.

Conclusions: 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.

Significance: 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 spectra and in particular the cross-spectra.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1016/j.clinph.2006.03.027
ISSNs: 1388-2457 (print)
Related URLs:
Keywords: local field potential, electromyograms, spectra analysis, coherence, harmonics, tremor
Subjects: R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
T Technology > TA Engineering (General). Civil engineering (General)
Q Science > QP Physiology
Divisions : University Structure - Pre August 2011 > Institute of Sound and Vibration Research > Human Sciences
ePrint ID: 46223
Accepted Date and Publication Date:
Date Deposited: 11 Jun 2007
Last Modified: 31 Mar 2016 12:21

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