Implicit sensorimotor adaptation following motor imagery


Error-driven sensorimotor adaptation relies on the mismatch between the predicted and actual sensory consequences of the movement. The consequence of this mismatch (sensory prediction error - SPE) results in implicit adaptive motor responses. Interestingly, motor imagery (MI), the internal simulation of the physical sensations of action in absence of overt execution, has also been shown to involve predictive mechanisms. However, it is unknown whether MI is sufficient to generate an SPE and lead to adaptive motor responses. Here, a reaching task with single-trial visuomotor perturbations was used in a fully within-subject design (n=30). It was hypothesized that providing an experimentally rotated visual feedback time-locked to the moment at which participants were asked to imagine reaching a target on trial n, would lead to an adaptive response in an actual reaching movement on trial n+1 (MI condition). The same rotated visual feedback was provided while participants were instructed to co-contract the upper arm muscles, irrespective of target position, to prevent them from performing meaningful MI (Control condition). In an Execution condition, participants physically performed the movement towards the target. Results revealed a small but significant post-rotation adaptive response opposite to the direction of the perturbation in both the MI and Control conditions. However, the magnitude of this bias was much larger in the Execution condition. These results indicate that SPEs can be generated even though a movement is not executed, but suggest an additional contribution of movement execution and/or dynamic proprioceptive signals in potentiating implicit visuomotor adaptation.