An explicit strategy facilitates adaptation to virtual surgeries by biasing the recruitment of existing synergies

Muscle synergies simplify motor control by mapping movement goals onto a reduced set of neural commands. However, how this modular architecture adapts during motor learning and the role of explicit strategies remain unclear. Here, we investigated adaptation to "virtual surgeries," perturbations of muscle pulling directions simulated in virtual reality, with and without explicit cues consisting of touching and naming the muscles most effective. Explicit cues increased reaction times and improved performance after both compatible surgeries, which could be compensated by recombining existing synergies, and incompatible surgeries, which required the exploration of new muscle patterns. After incompatible surgeries, however, performance gains were limited to conditions requiring only minor synergy reorganization. These findings suggest that explicit strategies primarily bias recombination toward existing synergies rather than forming new ones. Understanding the contributions of explicit processes can inform rehabilitation protocols and human-machine interfaces aimed at refining existing movements or acquiring new motor skills.