Separation of multiple motor memories through implicit and explicit processes

Acquisition of multiple motor skills without interference is a remarkable ability in daily life. During adaptation to opposing perturbations, a common paradigm to study this ability, each perturbation can be successfully learned when a contextual follow-through movement is associated with the direction of the perturbation. It is still unclear, however, to what extent this learning engages the cognitive explicit process and the implicit process. Here, we untangled the individual contributions of the explicit and implicit components while participants learned opposing visuomotor perturbations, with a second unperturbed follow-through movement. In experiment 1, we replicated previous adaptation results and showed that follow-through movements also allow learning for opposing visuomotor rotations. For one group of participants in experiment 2, we isolated strategic explicit learning, while for another group we isolated the implicit component. Our data showed that opposing perturbations could be fully learned by explicit strategies, but when strategy was restricted, distinct implicit processes contributed to learning. In experiment 3, we examined whether learning is influenced by the disparity between the follow-through contexts. We found that the location of follow-through targets had little effect on total learning, yet it led to more instances in which participants failed to learn the task. In experiment 4, we explored the generalization capability to untrained targets. Participants showed near-flat generalization of the implicit and explicit processes. Overall, our results indicate that follow-through contextual cues might activate, in part, top-down cognitive factors that influence not only the dynamics of the explicit learning but also the implicit process.NEW & NOTEWORTHY Acquisition of multiple motor skills is a remarkable ability in everyday activities. Yet, the contribution of implicit and explicit learning processes during learning of multiple motor skills is still unclear. We sought to dissociate this ability during learning opposing visuomotor rotations, each associated with a contextual follow-through movement. We show that follow-through contextual cues influence activity of both implicit and explicit processes, suggesting that context-based top-down cognitive factors influence not only the explicit learning but also the implicit process.