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Abstract

The aim of the study was to investigate tDCS effects on motor skill learning in a complex whole bodydynamic balance task (DBT). We hypothesized that tDCS over the supplementary motor area (SMA), aregion that is known to be involved in the control of multi-joint whole body movements, will resultin polarity specific changes in DBT learning. In a randomized sham-controlled, double-blinded paralleldesign, we applied 20 min of tDCS over the supplementary motor area (SMA) and prefrontal cortex (PFC)while subjects performed a DBT. Anodal tDCS over SMA with the cathode placed over contralateral PFCimpaired motor skill learning of the DBT compared to sham. This effect was still present on the second dayof training. Reversing the polarity (cathode over SMA, anode over PFC) did not affect motor skill learningneither on the first nor on the second day of training. To better disentangle whether the impaired motorskill learning was due to a modulation of SMA or PFC, we performed an additional control experiment.Here, we applied anodal tDCS over SMA together with a larger and presumably more ineffective electrode(cathode) over PFC. Interestingly this alternative tDCS electrode setup did not affect the outcome of DBTlearning. Our results provide novel evidence that a modulation of the (right) PFC seems to impair complexmulti-joint motor skill learning. Hence, future studies should take the positioning of both tDCS electrodesinto account when investigating complex motor skill learning.