title: Transcranial direct current stimulation: before, during, or after motor training?
abstract: Noninvasive brain stimulation has recently been used to augment motor training-induced plasticity. However, the exact time during which noninvasive brain stimulation can be combined with motor therapy to maximize neuroplasticity and behavioral changes is unknown. We conducted a randomized sham-controlled crossover trial to examine when (before, during, or after training) transcranial direct current stimulation (tDCS) should be applied to best reinforce motor training-induced plasticity in 12 healthy right-handed participants (mean age: 21.8±1.6) who underwent active or sham tDCS combined with motor training. Transcranial magnetic stimulation-elicited motor-evoked potentials from the right first dorsal interosseous muscle were recorded before (baseline) and immediately after each session. The training task comprised four practice trials - 3 min each (30 s pause between trials) - of repetitive finger movements (thumb abduction/adduction) with the right hand. Anodal tDCS (1 mA, 13 min, on the motor primary cortex) was applied before, during, and after the training. Compared with baseline motor-evoked potentials and the sham condition, tDCS that was applied before, but not during or after, the motor task enhanced corticospinal excitability. These data suggest that tDCS performed before - not during or after - promotes optimization of motor training-induced plasticity.
authors.affiliation: aApplied Neuroscience Laboratory, Federal University of Pernambuco, Recife, Brazil bSpaulding Rehabilitation Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Cabral
authors.forename: Adriana
authors.initials: A
authors.lastname: Baltar
authors.forename: Rebeka
authors.initials: R
authors.lastname: Borba
authors.forename: Silvana
authors.initials: S
authors.lastname: Galvão
authors.forename: Luciana
authors.initials: L
authors.lastname: Santos
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
authors.forename: Kátia
authors.initials: K
authors.lastname: Monte-Silva
mesh_terms: D004311:Double-Blind Method; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D013663:Teaching / Q000379:methods*; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult