title: Bilateral tDCS on Primary Motor Cortex: Effects on Fast Arm Reaching Tasks.
abstract: BACKGROUND
  The effects produced by transcranial direct current stimulation (tDCS) applied to the motor system have been widely studied in the past, chiefly focused on primary motor cortex (M1) excitability. However, the effects on functional tasks are less well documented.
  
  
  OBJECTIVE
  This study aims to evaluate the effect of tDCS-M1 on goal-oriented actions (i.e., arm-reaching movements; ARM), in a reaction-time protocol.
  
  
  METHODS
  13 healthy subjects executed dominant ARM as fast as possible to one of two targets in front of them while surface EMG was recorded. Participants performed three different sessions. In each session they first executed ARM (Pre), then received tDCS, and finally executed Post, similar to Pre. Subjects received three different types of tDCS, one per session: In one session the anode was on right-M1 (AR), and the cathode on the left-M1 (CL), thus termed AR-CL; AL-CR reversed the montage; and Sham session was applied likewise. Real stimulation was 1mA-10min while subjects at rest. Three different variables and their coefficients of variation (CV) were analyzed: Premotor times (PMT), reaction-times (RT) and movement-times (MT).
  
  
  RESULTS
  triceps-PMT were significantly increased at Post-Sham, suggesting fatigue. Results obtained with real tDCS were not different depending on the montage used, in both cases PMT were significantly reduced in all recorded muscles. RT and MT did not change for real or sham stimulation. RT-CV and PMT-CV were reduced after all stimulation protocols.
  
  
  CONCLUSIONS
  tDCS reduces premotor time and fatigability during the execution of fast motor tasks. Possible underlying mechanisms are discussed.
authors.affiliation: Neuroscience and Motor Control Group (NEUROcom), Department of Medicine, INEF Galicia and Biomedical Research Institute of A Coruña (INIBIC), University of A Coruña, A Coruña, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Arias
authors.affiliation: Neuroscience and Motor Control Group (NEUROcom), Department of Medicine, INEF Galicia and Biomedical Research Institute of A Coruña (INIBIC), University of A Coruña, A Coruña, Spain.
authors.forename: Yoanna
authors.initials: Y
authors.lastname: Corral-Bergantiños
authors.affiliation: Neuroscience and Motor Control Group (NEUROcom), Department of Medicine, INEF Galicia and Biomedical Research Institute of A Coruña (INIBIC), University of A Coruña, A Coruña, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Robles-García
authors.affiliation: Neuroscience and Motor Control Group (NEUROcom), Department of Medicine, INEF Galicia and Biomedical Research Institute of A Coruña (INIBIC), University of A Coruña, A Coruña, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Madrid
authors.affiliation: FENNSI Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Oliviero
authors.affiliation: Neuroscience and Motor Control Group (NEUROcom), Department of Medicine, INEF Galicia and Biomedical Research Institute of A Coruña (INIBIC), University of A Coruña, A Coruña, Spain.|Centro de Estimulación Cerebral de Galicia, A Coruña, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Cudeiro
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology; D011930:Reaction Time; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult