Does transcranial direct current stimulation of the primary motor cortex improve implicit motor sequence learning in Parkinson's disease?

Abstract Implicit motor sequence learning (IMSL) enables us to perform multiple single movements in a specific sequential order and is involved many of our daily activities (e.g., reaching, walking). Acquisition IMSL has been shown be significantly impaired Parkinson’s disease (PD). Research healthy individuals shows the potential for transcranial direct current stimulation (tDCS), non-invasive brain technique, over primary cortex (M1) enhance IMSL. In this study, we investigated M1 tDCS during (acquisition), five minutes post-tDCS (short-term consolidation) one-week (long-term with PD. Using sham-controlled, counterbalanced, double-blind design, effects on 35 persons PD controls (HC). Linear Mixed Models were used analyze sequence-specific (primary outcome) general (secondary outcome), as measured by serial reaction time task. Anodal improved (M=96.11ms post-anodal, M=41.16ms post-sham), p<.001, but deteriorated matched HC (M=53.26ms M=76.355ms), p=.016, when cognitive functioning intact. patients mild impairment, anodal enhanced flexibility, evidenced more flexible responses unexpected stimuli long-term consolidation phase (M=630.96ms M=691.83ms p=.029. We provide evidence that tDCS-induced neuroplastic do not follow linear rules, are dependent status basal ganglia functioning. enhances PD, deteriorates HC, Potentially, beneficially modulates abnormal cortical-subcortical network activity occurs detrimental effect unimpaired. These findings add body exerts its behavioral through modulation dopaminergic system. Category Technology Methods Clinical Research: 9. Transcranial Direct Current Stimulation (tDCS) Keywords: Parkinson's disease, tDCS, learning,