The role of somatosensation in automatic visuo-motor control: a comparison of congenital and acquired sensory loss

Abstract Studies of chronically deafferented participants have illuminated how regaining some motor control after adult-onset loss proprioceptive and touch input depends heavily on cognitive control. In this study we contrasted the performance one such man, IW, with KS, a woman born without any somatosensory fibres. We postulated that her life-long absence proprioception might allowed to automate simple visually-guided actions, something IW appears unable achieve. tested these two, two age-matched groups, writing drawing tasks performed an audio-verbal echoing task added demand. common other studies skilled action, dual was shown affect visuo-motor in controls, less well-controlled writing, evident as increases path speed reduction curvature trial duration. found little evidence able even simplest no for automaticity his writing. contrast, KS showed selective increase signature under dual-task conditions, suggesting ability most familiar also tracing templates mirror-reversed imposes powerful planning challenge. Both conflict, did shapes sharp corners. Overall, much faster than controls complete shapes, consistent visuo-proprioceptive whereas slower especially corners became sharper. She dramatically improved short period practice while not. conclude who developed from birth proprioception, may visually derived movement not control, seen IW. This but impaired initial attempts at mirror-tracing. lost somatosensation adult, cannot guided actions.