Dopaminergic modulation of long-lasting direct current-induced cortical excitability changes in the human motor cortex

Introduction: Dopaminergic mechanisms participate in NMDA receptor-dependent neuroplasticity, as animal experiments have shown. This may be similar in humans, where dopamine influences learning and memory. We tested the role of dopamine in human cortical neuroplasticity. Therefore, transcranial direct current stimulation (tDCS) of the primary motor cortex was used to induce NMDA receptor-dependent excitability modulations. Methods: According to standard protocols, 9min cathodal or 13min anodal tDCS, which are known to induce motor cortical excitability reductions or enhancements outlasting the stimulation for ab…