Intrinsic rewards modulate sensorimotor adaptation

Abstract Recent studies have demonstrated that task success signals can modulate behavioral changes during sensorimotor adaptation tasks, primarily through the engagement of explicit processes. In a series of reaching experiments with human participants, we explore a potential interaction between reward-based learning and implicit adaptation, using a method in which feedback is not contingent on task performance. We varied the size of the target to compare conditions in which visual feedback indicated an invariant angular error that either hit or missed the target. Hitting the target attenuated the behavioral changes from adaptation, an effect we attribute to the generation of an intrinsic reward signal. We evaluated two models, one in which reward and adaptation systems operate in parallel, and a second in which reward acts directly on the adaptation system. The results favor the latter, consistent with evidence showing communication, and possible overlap, between neural substrates underlying reward-based learning and sensorimotor adaptation.