title: Modulation of training by single-session transcranial direct current stimulation to the intact motor cortex enhances motor skill acquisition of the paretic hand.
abstract: OBJECTIVE
  Mechanisms of skill learning are paramount components for stroke recovery. Recent noninvasive brain stimulation studies demonstrated that decreasing activity in the contralesional motor cortex might be beneficial, providing transient functional improvements after stroke. The more crucial question, however, is whether this intervention can also enhance the acquisition of complex motor tasks, yielding longer-lasting functional improvements. In the present study, we tested the capacity of cathodal transcranial direct current stimulation (tDCS) applied over the contralesional motor cortex during training to enhance the acquisition and retention of complex sequential finger movements of the paretic hand.
  
  
  METHODS
  Twelve well-recovered chronic patients with subcortical stroke attended 2 training sessions during which either cathodal tDCS or a sham intervention were applied to the contralesional motor cortex in a double-blind, crossover design. Two different motor sequences, matched for their degree of complexity, were tested in a counterbalanced order during as well as 90 minutes and 24 hours after the intervention. Potential underlying mechanisms were evaluated with transcranial magnetic stimulation.
  
  
  RESULTS
  tDCS facilitated the acquisition of a new motor skill compared with sham stimulation (P=0.04) yielding better task retention results. A significant correlation was observed between the tDCS-induced improvement during training and the tDCS-induced changes of intracortical inhibition (R(2)=0.63).
  
  
  CONCLUSIONS
  These results indicate that tDCS is a promising tool to improve not only motor behavior, but also procedural learning. They further underline the potential of noninvasive brain stimulation as an adjuvant treatment for long-term recovery, at least in patients with mild functional impairment after stroke.
authors.affiliation: Brain Imaging and Neurostimulation Labor, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Máximo
authors.initials: M
authors.lastname: Zimerman
authors.forename: Kirstin F
authors.initials: KF
authors.lastname: Heise
authors.forename: Julia
authors.initials: J
authors.lastname: Hoppe
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Cohen
authors.forename: Christian
authors.initials: C
authors.lastname: Gerloff
authors.forename: Friedhelm C
authors.initials: FC
authors.lastname: Hummel
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D003627:Data Interpretation, Statistical; D004311:Double-Blind Method; D004558:Electric Stimulation / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology; D006225:Hand / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology* / Q000503:physiopathology; D009048:Motor Skills / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009128:Muscle Spasticity / Q000209:etiology / Q000534:rehabilitation; D009483:Neuropsychological Tests; D010243:Paralysis / Q000209:etiology / Q000534:rehabilitation*; D020521:Stroke / Q000150:complications; D000071939:Stroke Rehabilitation; D050781:Transcranial Magnetic Stimulation