Visuo-motor rotation influences representational acuity but not space representation

Prism adaptation is a well-known experimental procedure to study sensorimotor plasticity. It has been shown that following prism exposure, after-effects are not only restricted to the sensorimotor level but extend as well to spatial cognition. In the present study, we used a visuo-motor rotation task which approaches the perturbations induced by prism exposure. We induced either leftward or rightward 15-degree rotations and we presented the perturbation either abruptly (from one trial to the next) or gradually (over a 34-trial transition). First, we found that none of the conditions produced cognitive after-effects in perceptive line bisection task. This result has a strong methodological impact for prospective investigations focusing on sensorimotor plasticity while sparing space cognition; it is particularly relevant when investigating sensorimotor plasticity in patients with specific representational feature to preserve from aggravation. Second, another interesting result was the increase of the sensitivity with which we discriminate the center of the line, that we propose to call representational acuity. It improved following the perturbation more particularly after gradual exposure and persisted for some time after the sensorimotor adaptation. These innovative results are discussed in terms of sensorimotor processes underpinning the transfer of visuomotor plasticity to spatial cognition.