Sensorimotor adaptation to visual distortions with different kinematic coupling.

We investigated the mechanisms of sensorimotor adaptation by sequentially exposing human subjects to different visual distortions. Subjects performed a manual tracking task, while the relationship between their actual finger movement and its visual feedback was manipulated either by a position-to-position (PP), or by a position-to-velocity (PV) transformation. The outcome confirmed previous findings, in that adaptation to PP facilitated the subsequent adaptation to a second, additional PP. More importantly, our present data documented that pre-exposure to PP interferes with the subsequent adaptation to PV, and vice versa. Thus, we observed anterograde interference between two transformations of common physical nature (i.e., visual), but different kinematic coupling. When previous work on sequential adaptation to visual and mechanical transformations is reconsidered in light of this finding, converging evidence is yielded in favor of a distributed adaptive mechanism, where the magnitude of interference between two successive adaptation sessions depends on the overlap of the involved neural structures.