title: Changes in corticomotor excitability and intracortical inhibition of the primary motor cortex forearm area induced by anodal tDCS.
abstract: OBJECTIVE
  Previous studies have investigated how tDCS over the primary motor cortex modulates excitability in the intrinsic hand muscles. Here, we tested if tDCS changes corticomotor excitability and/or cortical inhibition when measured in the extensor carpi radialis (ECR) and if these aftereffects can be successfully assessed during controlled muscle contraction.
  
  
  METHODS
  We implemented a double blind cross-over design in which participants (n = 16) completed two sessions where the aftereffects of 20 min of 1 mA (0.04 mA/cm2) anodal vs sham tDCS were tested in a resting muscle, and two more sessions where the aftereffects of anodal vs sham tDCS were tested in an active muscle.
  
  
  RESULTS
  Anodal tDCS increased corticomotor excitability in ECR when aftereffects were measured with a low-level controlled muscle contraction. Furthermore, anodal tDCS decreased short interval intracortical inhibition but only when measured at rest and after non-responders (n = 2) were removed. We found no changes in the cortical silent period.
  
  
  CONCLUSIONS
  These findings suggest that targeting more proximal muscles in the upper limb with anodal tDCS is achievable and corticomotor excitability can be assessed in the presence of a low-level controlled contraction of the target muscle.
authors.affiliation: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium.
authors.forename: Xue
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Woolley
authors.affiliation: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium.
authors.forename: Stephan P
authors.initials: SP
authors.lastname: Swinnen
authors.affiliation: Research Group for Neuromotor Rehabilitation, Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Hilde
authors.initials: H
authors.lastname: Feys
authors.affiliation: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium; REVAL Rehabilitation Research Centre, Biomedical Research Institute, Hasselt University, Hasselt, Belgium.
authors.forename: Raf
authors.initials: R
authors.lastname: Meesen
authors.affiliation: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium; Neural Control of Movement Laboratory, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.
authors.forename: Nicole
authors.initials: N
authors.lastname: Wenderoth
mesh_terms: D004311:Double-Blind Method; D004576:Electromyography; D005260:Female; D005542:Forearm / Q000502:physiology*; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology*; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology; D009474:Neurons / Q000166:cytology; D011795:Surveys and Questionnaires; D065908:Transcranial Direct Current Stimulation; D014953:Wrist / Q000502:physiology; D055815:Young Adult