TY - JOUR T1 - Motor training strengthens corticospinal suppression during movement preparation JF - bioRxiv DO - 10.1101/2020.02.14.948877 SP - 2020.02.14.948877 AU - Pierre Vassiliadis AU - Gerard Derosiere AU - Julien Grandjean AU - Julie Duque Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/02/14/2020.02.14.948877.abstract N2 - Motor training improves the efficiency of trained movements and modifies neural activity at rest and during motor execution. Training may also shape preparatory processes but the neural correlates and the potential behavioral relevance of changes at the level of action preparation remain unclear. In humans, transcranial magnetic stimulation (TMS) studies have shown that movement preparation is accompanied by a suppression of corticospinal (CS) excitability relative to a baseline measure; a phenomenon called preparatory suppression. Here, we trained participants to initiate quick movements in an instructed-delay reaction time (RT) task and investigated resting CS excitability as well as preparatory suppression over the practice blocks. We found that training speeds up motor initiation, with no repercussion on error rates. Moreover, training increased baseline CS excitability and deepened preparatory suppression. Importantly, training-related changes in preparatory suppression were correlated to behavioral improvements: the subjects who showed a stronger expansion of preparatory suppression were also those exhibiting larger gains in RTs. Finally, in line with previous data, we observed a trial-by-trial relationship between the amount of preparatory suppression and the subsequent RT: subjects responded faster on trials with more preparatory suppression. Strikingly though, such a dependency of RTs on preparatory suppression was tuned by the amount of training performed: while it was not evident early on, the link emerged during the later practice blocks. Overall, our data indicate that training induces changes in motor preparatory processes that are linked to an enhanced ability to initiate fast movements.Significance statement Any movement is preceded by a period of preparation which involves significant changes in the activity of the motor system, including a broad suppression of the corticospinal output pathway, commonly referred to as preparatory suppression in human studies. Whether training can alter such preparatory activity is unknown. Here, we show that motor training leads to a strengthening of preparatory suppression in an instructed-delay reaction time (RT) task, and that such change is related to a shortening of RTs. Moreover, at the single-trial level, we observed a dependency of RTs on preparatory suppression which developed over training: the stronger the preparatory suppression, the faster the RT. These results indicate that motor training can alter motor preparatory activity in a behaviorally-relevant manner. ER -