Abstract
Previous work has demonstrated that the planning of reaches to visual (V) and proprioceptive (P) targets is mediated by distinct sensorimotor transformations (Bernier et al. 2007). In this study we asked how sensory information is integrated, and hence how these sensorimotor transformations interact, when reaching to a multimodal (visual + proprioceptive (VP)) target. Subjects trained to reach with distorted hand-cursor feedback, such that they saw a cursor that was rotated (resulting in a change of movement direction and extent) or translated (resulting in a change of movement direction) relative to their actual hand movement. Following training trials with the cursor, subjects reached to V, P and 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 distortion. 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 indicate that following training with a visuomotor distortion subjects rely on proprioceptive information when reaching to VP targets, implying that sensorimotor transformations do not interact. Furthermore results indicate that adaptation of reaches to V and P targets depend on the distortion presented such that training with a visuomotor rotation distortion affects the processing of both visual and proprioceptive input, while a translation distortion affects only the processing of visual input.Acknowledgments: Research support: Natural Sciences and Engineering Research Council (EKC)