Abstract
Our central nervous system (CNS) uses both visual and proprioceptive information about the locations of our body parts to enable us to move throughout the environment and complete our daily activities. We have previously shown that the brain can change how it weights sensory cues when reaching to bimodal targets (i.e. targets defined by visual and proprioceptive cues), relying more on proprioception after experiencing greater errors (i.e. greater variability) when reaching to visual targets. In the present study, we asked if similar reweighting strategies are engaged after experiencing greater errors when reaching to proprioceptive targets. Participants reached to visual (V), proprioceptive (P; left index finger) or visual + proprioceptive (VP; seen left index finger) targets. Inaccurate endpoint visual feedback was provided on V and P reaches, such that on P reaches the seen horizontal error was greater than (three times) the actual horizontal error achieved and on V reaches the seen horizontal error was smaller than (one third) the actual horizontal error achieved. No feedback was provided on VP reaches. Comparison of reach endpoints revealed that subjects did not change their sensory weighting strategy after experiencing greater variability when reaching to P targets. Thus, the CNS does not always reweight sensory cues after experiencing increased errors, suggesting that the brain processes errors associated with proprioceptive versus visual targets in a different manner.Acknowledgments: Natural Sciences and Engineering Research Council (EKC)