A systematic method to quantify the presence of cross-talk in stimulus-evoked EMG responses: Implications for TMS studies

Selvanayagam, Victor S., Riek, Stephan and Carroll, Timothy J. (2012) A systematic method to quantify the presence of cross-talk in stimulus-evoked EMG responses: Implications for TMS studies. Journal of Applied Physiology, 112 2: 259-265. doi:10.1152/japplphysiol.00558.2011


Author Selvanayagam, Victor S.
Riek, Stephan
Carroll, Timothy J.
Title A systematic method to quantify the presence of cross-talk in stimulus-evoked EMG responses: Implications for TMS studies
Journal name Journal of Applied Physiology   Check publisher's open access policy
ISSN 8750-7587
1522-1601
Publication date 2012-01
Year available 2011
Sub-type Article (original research)
DOI 10.1152/japplphysiol.00558.2011
Volume 112
Issue 2
Start page 259
End page 265
Total pages 7
Place of publication Bethesda, MD, United States
Publisher American Physiological Society
Collection year 2012
Language eng
Abstract Surface electromyography (EMG) responses to noninvasive nerve and brain stimulation are routinely used to provide insight into neural function in humans. However, this could lead to erroneous conclusions if evoked EMG responses contain significant contributions from neighboring muscles (i.e., due to “cross-talk”). We addressed this issue with a simple nerve stimulation method to provide quantitative information regarding the size of EMG cross-talk between muscles of the forearm and hand. Peak to peak amplitude of EMG responses to electrical stimulation of the radial, median, and ulnar nerves (i.e., M-waves) were plotted against stimulation intensity for four wrist muscles and two hand muscles (n = 12). Since electrical stimulation can selectively activate specific groups of muscles, the method can differentiate between evoked EMG arising from target muscles and EMG cross-talk arising from nontarget muscles. Intramuscular EMG responses to nerve stimulation and root mean square EMG produced during maximal voluntary contractions (MVC) of the wrist were recorded for comparison. Cross-talk was present in evoked surface EMG responses recorded from all nontarget wrist (5.05–39.38% Mmax) and hand muscles (1.50–24.25% Mmax) and to a lesser degree in intramuscular EMG signals (∼3.7% Mmax). The degree of cross-talk was comparable for stimulus-evoked responses and voluntary activity recorded during MVC. Since cross-talk can make a considerable contribution to EMG responses in forearm and hand muscles, care is required to avoid misinterpretation of EMG data. The multiple nerve stimulation method described here can be used to quantify the potential contribution of EMG cross-talk in transcranial magnetic stimulation and reflex studies.
Keyword Surface electromyography
Nerve stimulation
Reflex
Biomechanics
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Online November 2011

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Human Movement and Nutrition Sciences Publications
 
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