Evidence for Distinct, Differentially Adaptable Sensorimotor Transformations for Reaches to Visual and Proprioceptive Targets

1 Laboratoire de Neurobiologie de la Cognition, Centre National de la Recherche Scientifique and Aix Marseille Université, Marseille, and 2 Unité Mixte de Recherche Mouvement and Perception, Centre National de la Recherche Scientifique and Aix Marseille Université, Marseille, France Submitted 22 May 2007; accepted in final form 11 July 2007 Recent evidence suggests that planning a reaching movement entails similar stages and common networks irrespective of whether the target location is defined through visual or proprioceptive cues. Here we test whether the transformations that convert the sensory information regarding target location into the required motor output are common for both types of reaches. To do so, we adaptively modified these sensorimotor transformations through exposure to displacing prisms and hypothesized that if they are common to both types of reaches, the aftereffects observed for reaches to visual targets would generalize to reaches to a proprioceptive target. Subjects ( n = 16) were divided into two groups that differed with respect to the sensory modality of the targets (visual or proprioceptive) used in the pre- and posttests. The adaptation phase was identical for both groups and consisted of movements toward visual targets while wearing 10.5° horizontally displacing prisms. We observed large aftereffects consistent with the magnitude of the prism-induced shift when reaching toward visual targets in the posttest, but no significant aftereffects for movements toward the proprioceptive target. These results provide evidence that distinct, differentially adaptable sensorimotor transformations underlie the planning of reaches to visual and proprioceptive targets. Address for reprint requests and other correspondence: J. Blouin, Lab. de Neurobiologie de la Cognition, CNRS and Aix Marseille Univ., 3, Place Victor Hugo, 13331 Marseille Cedex 3 France (E-mail: jean.blouin{at}univ-provence.fr )