Adaptation to proprioceptive targets following visuomotor adaptation

In the following study, we asked if reaches to proprioceptive targets are updated following reach training with a gradually introduced visuomotor perturbation. Subjects trained to reach with distorted hand-cursor feedback, such that they saw a cursor that was rotated or translated relative to their actual hand movement. Following reach training trials with the cursor, subjects reached to Visual (V), Proprioceptive (P) and Visual + Proprioceptive (VP) targets with no visual feedback of their hand. Comparison of reach endpoints revealed that reaches to VP targets followed similar trends as reaches to P targets, regardless of the training distortion introduced. After reaching with a rotated cursor, subjects adapted their reaches to all target types in a similar manner. However, after reaching with a translated cursor, subjects adapted their reach to V targets only. Taken together, these results show that following training with a visuomotor distortion, subjects primarily rely on proprioceptive information when reaching to VP targets. Furthermore, results indicate that reach adaptation to P targets depends on the distortion presented. Training with a rotation distortion leads to changes in reaches to both V and P targets, while a translation distortion, which introduces a constant discrepancy between visual and proprioceptive estimates of hand position throughout the reach, affects changes to V but not P targets.