title: Selectivity of conventional electrodes for recording motor evoked potentials: An investigation with high-density surface electromyography.
abstract: 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.
  
  
  
  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.
  
  
  
  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).
  
  
  
  MEPs recorded with conventional EMG may contain crosstalk from non-target muscles, especially when the stimulation is applied at rest. Muscle Nerve 55: 828-834, 2017.
authors.affiliation: Graduate Program in Rehabilitation Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Alessio
authors.initials: A
authors.lastname: Gallina
authors.affiliation: Graduate Program in Rehabilitation Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Sue
authors.initials: S
authors.lastname: Peters
authors.affiliation: Department of Physical Therapy, University of British Columbia, 212 Friedman Building, 2177 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Neva
authors.affiliation: Department of Physical Therapy, University of British Columbia, 212 Friedman Building, 2177 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada.
authors.forename: Lara A
authors.initials: LA
authors.lastname: Boyd
authors.affiliation: Department of Physical Therapy, University of British Columbia, 212 Friedman Building, 2177 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada.
authors.forename: S Jayne
authors.initials: SJ
authors.lastname: Garland
mesh_terms: D000328:Adult; D004566:Electrodes; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006225:Hand / Q000294:innervation; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: electromyography; forearm; high-density surface electromyography; motor evoked potential; transcranial magnetic stimulation; wrist extensor muscles