Selective Enhancement of Proprioceptive Acuity Following Motor

23 24 It is well recognized that the brain uses sensory information to accurately 25 produce motor commands. Indeed, most research into the relationship between 26 sensory and motor systems has focused on how sensory information modulates 27 motor function. In contrast, recent studies have begun to investigate the reverse: 28 how sensory and perceptual systems are tuned based on motor function, and 29 specifically motor learning. Here we investigated changes to human 30 proprioceptive acuity following recent motor learning. Sensitivity to small 31 displacements of the hand was measured before and after 10 minutes of motor 32 learning, during which subjects grasped the handle of a robotic arm and guided a 33 cursor to a series of visual targets randomly located within a small workspace 34 region. We used a novel method of assessing proprioceptive acuity that avoids 35 active movement, inter-hemispheric transfer and inter-modality coordinate 36 transformations. We found that proprioceptive acuity improved following motor 37 learning, but only in the region of the arm’s workspace explored during learning. 38 No proprioceptive improvement was observed when motor learning was 39 performed in a different location, or when subjects passively experienced limb 40 trajectories matched to those of subjects who actively performed motor learning. 41 Our findings support the idea that sensory changes occur in parallel with 42 changes to motor commands during motor learning. 43