Anodal tDCS over Primary Motor Cortex Provides No Advantage to Learning Motor Sequences via Observation.

Apšvalka, Dace 
Ramsey, Richard 
Cross, Emily S 

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When learning a new motor skill, we benefit from watching others. It has been suggested that observation of others' actions can build a motor representation in the observer, and as such, physical and observational learning might share a similar neural basis. If physical and observational learning share a similar neural basis, then motor cortex stimulation during observational practice should similarly enhance learning by observation as it does through physical practice. Here, we used transcranial direct-current stimulation (tDCS) to address whether anodal stimulation to M1 during observational training facilitates skill acquisition. Participants learned keypress sequences across four consecutive days of observational practice while receiving active or sham stimulation over M1. The results demonstrated that active stimulation provided no advantage to skill learning over sham stimulation. Further, Bayesian analyses revealed evidence in favour of the null hypothesis across our dependent measures. Our findings therefore provide no support for the hypothesis that excitatory M1 stimulation can enhance observational learning in a similar manner to physical learning. More generally, the results add to a growing literature that suggests that the effects of tDCS tend to be small, inconsistent, and hard to replicate. Future tDCS research should consider these factors when designing experimental procedures.

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Adolescent, Adult, Behavior Observation Techniques, Female, Humans, Imitative Behavior, Learning, Male, Motor Cortex, Motor Skills, Photic Stimulation, Psychomotor Performance, Transcranial Direct Current Stimulation, Young Adult
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Neural Plasticity
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Hindawi Publishing Corporation
Medical Research Council (MC_UU_00005/1)
This work was supported by the Ministry of Defence of the United Kingdom Defence Science and Technology Laboratory (Grant no. DSTLX-1000083177 to Emily S. Cross and Richard Ramsey), the Economic and Social Research Council (Grant no. ES/K001884/1 to Richard Ramsey and ES/K001892/1 to Emily S. Cross), and the funding from the European Commission to Emily S. Cross (CIG11- 2012-322256 and ERC-2015-STG-677270).