Visuomotor adaptation does not recalibrate kinesthetic sense of felt hand path.

Motor control relies on multiple sources of information. To estimate the position and motion of the hand, the brain uses both vision and body-position (proprioception and kinesthesia) senses from sensors in the muscles, tendons, joints, and skin. Although performance is better when more than one sensory modality is present, visuomotor adaptation suggests that people tend to rely much more on visual information of the hand to guide their arm movements to targets, even when the visual information and kinesthetic information about the hand motion are in conflict. The aim of this study is to test whether adapting hand movements in response to false visual feedback of the hand will result in the change or recalibration of the kinesthetic sense of hand motion. The advantage of this cross-sensory recalibration would ensure on-line consistency between the senses. To test this, we mapped participants' sensitivity to tilted and curved hand paths and then examined whether adapting their hand movements in response to false visual feedback affected their felt sense of hand path. We found that participants could accurately estimate hand path directions and curvature after adapting to false visual feedback of their hand when reaching to targets. Our results suggest that although vision can override kinesthesia to recalibrate arm motor commands, it does not recalibrate the kinesthetic sense of hand path geometry.