Motor adaptation and manual transfer: insight into the persistent nature of sensorimotor representations.

It is well known that sensorimotor memories are built and updated through experience with objects. These representations are useful to anticipatory and feedforward control processes that preset grip and load forces during lifting. When individuals lift objects with qualities that are not congruent with their memory-derived expectations, feedback processes adjust motor plans to achieve successful lifts and contribute to the updating of the stored representations. The two experiments presented examine motor adaptation to an illusory size-weight lifting task, and the transfer of this motor adaptation to the unexposed hand. In Experiment 1, performers acquired motor adaptation with their right hand and transfer was measured on their left hand. In Experiment 2, adaptation was acquired with the left hand and transfer was measured on the right hand. In order to investigate the persistence of sensorimotor memories, these experiments measure adaptation, retention, and transfer after 15min and 24h delay periods. Both experiments confirm that experience with objects leads to adaptation of force scaling processes, that these adaptations transcend effector and are persistent. The results are discussed in terms favouring interpretations that describe motor adaptations to illusion as being centrally available. Copyright 2009 Elsevier Inc. All rights reserved.