Imperial College London
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ProfessorDarioFarina

Faculty of Engineering, Department of Bioengineering

Chair in Neurorehabilitation Engineering
 
 
 
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Contact

 

+44 (0)20 7594 1387d.farina Website

 
 
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Location

 

RSM 4.15Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Dideriksen:2019:10.1371/journal.pcbi.1006985,
author = {Dideriksen, JL and Farina, D},
doi = {10.1371/journal.pcbi.1006985},
journal = {PLoS Computational Biology},
title = {Amplitude cancellation influences the association between frequency components in the neural drive to muscle and the rectified EMG signal},
url = {http://dx.doi.org/10.1371/journal.pcbi.1006985},
volume = {15},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The rectified surface EMG signal is commonly used as an estimator of the neural drive to muscles and therefore to infer sources of synaptic input to motor neurons. Loss of EMG amplitude due to the overlap of motor unit action potentials (amplitude cancellation), however, may distort the spectrum of the rectified EMG and thereby its correlation with the neural drive. In this study, we investigated the impact of amplitude cancelation on this correlation using analytical derivations and a computational model of motor neuron activity, force, and the EMG signal. First, we demonstrated analytically that an ideal rectified EMG signal without amplitude cancellation (EMGnc) is superior to the actual rectified EMG signal as estimator of the neural drive to muscle. This observation was confirmed by the simulations, as the average coefficient of determination (r2) between the neural drive in the 1–30 Hz band and EMGnc (0.59±0.08) was matched by the correlation between the rectified EMG and the neural drive only when the level of amplitude cancellation was low (<40%) at low contraction levels (<5% of maximum voluntary contraction force; MVC). This correlation, however, decreased linearly with amplitude cancellation (r = -0.83) to values of r2 <0.2 at amplitude cancellation levels >60% (contraction levels >15% MVC). Moreover, the simulations showed that a stronger (i.e. more variable) neural drive implied a stronger correlation between the rectified EMG and the neural drive and that amplitude cancellation distorted this correlation mainly for low-frequency components (<5 Hz) of the neural drive. In conclusion, the results indicate that amplitude cancellation distorts the spectrum of the rectified EMG signal. This implies that valid use of the rectified EMG as an estimator of the neural drive requires low contraction levels and/or strong common synaptic input to the motor neurons.
AU  - Dideriksen,JL
AU  - Farina,D
DO  - 10.1371/journal.pcbi.1006985
PY  - 2019///
SN  - 1553-734X
TI  - Amplitude cancellation influences the association between frequency components in the neural drive to muscle and the rectified EMG signal
T2  - PLoS Computational Biology
UR  - http://dx.doi.org/10.1371/journal.pcbi.1006985
UR  - http://hdl.handle.net/10044/1/70099
VL  - 15
ER  -
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