Selectivity of conventional electrodes for recording motor evoked potentials: an investigation with high-density surface electromyography

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Colleges, School and Institutes


Introduction: The objective of this study was to determine whether motor evoked potentials (MEPs) elicited with transcranial magnetic stimulation and measured with conventional bipolar electromyography (EMG) are influenced by crosstalk from non-target muscles.

Methods: MEPs were recorded in healthy participants using conventional EMG electrodes placed over the extensor carpi radialis muscle (ECR) and high-density surface EMG (HDsEMG). Fifty MEPs at 120% resting and active motor threshold were recorded. To determine the contribution of ECR to the MEPs, the amplitude distribution across HDsEMG channels was correlated with EMG activity recorded during a wrist extension task.

Results: Whereas the conventional EMG identified MEPs from ECR in >90% of the stimulations, HDsEMG revealed that spatial amplitude distribution representative of ECR activation was observed less frequently at rest than while holding a contraction (P < 0.001).

Conclusions: MEPs recorded with conventional EMG may contain crosstalk from non-target muscles, especially when the stimulation is applied at rest.


Original languageEnglish
Pages (from-to)828-834
Number of pages7
JournalMuscle & Nerve
Issue number6
Early online date27 Jan 2017
Publication statusPublished - 22 May 2017


  • electromyography, forearm, high-density surface electromyography, motor evoked potential, ranscranial magnetic stimulation, wristextensor muscles