Motor adaptation and proprioceptive recalibration in the absence of on-line movement corrections


Reaching to targets in a virtual reality environment with misaligned visual feedback of the hand results in changes in movements (motor adaptation) and sense of felt hand position (proprioceptive recalibration) (Cressman and Henriques, 2009). In the current study we looked to determine if changes in the motor and sensory system are dependent on experiencing endpoint feedback and hence completing on-line movement corrections to the target during reach training. Subjects performed a "shooting task" to three targets with a cursor that was rotated 30° counter-clockwise relative to their hand. Specifically, subjects were instructed to move as quickly and accurately as possible, such that the visual representation of their hand passed through the target location. Thus, subjects did not complete on-line movement corrections and the visual representation of their hand did not stop at the target. Following training, subjects reached to the same three targets without visual feedback to determine motor adaptation in the form of aftereffects and provided estimates of their hand position relative to the three targets to establish proprioceptive recalibration. Results revealed that subjects adapted their reaches to all three targets and recalibrated their sense of felt hand position. Moreover, motor and sensory changes were similar in magnitude to those observed when subjects aimed to targets and performed on-line movement corrections (Cressman and Henriques, 2009). Thus, motor adaptation and proprioceptive recalibration are not dependent on on-line corrections. Furthermore, motor and sensory changes arise even when subjects do not have the experience of their "hand" landing on a target.

Acknowledgments: Supported by NSERC