"Don't let the right hand know what your left hand is doing": Interlimb visuomotor adaption with abrupt and gradual perturbation


Humans can compensate for changes to the sensorimotor system and the environment by rapidly adapting their movements to achieve success (i.e., sensorimotor remapping). When individuals adapt to an abruptly introduced change (remapping A) using one limb and then have to adapt to an opposite (remapping B) using another limb, interference between the two memories is observed. Interference occurs because these memories presumably compete for the same neural resources. The present study was designed to determine if the observed interference can be eliminated or reduced if the resources that the two memories depend on, can be separated. Two groups of participants adapted to abrupt and gradual visuomotor perturbations with different arms because there is evidence that adaptation to these forms of perturbations recruits distinct brain regions. Group 1 (RLR) adapted to an abrupt clockwise visuomotor rotation A with their Right-limb followed by an opposite, gradually imposed rotation B with the Left-limb. Interference was assessed by re-exposing subjects to rotation A 24 hours later, again with the Right-limb. Group 2 (LRL) performed the same task, but with the opposite hand order. The results revealed no interference between the memories acquired following abrupt and gradual motor adaptation. The work strengthens the view that abrupt and gradual adaption rely on different mechanisms and, likely, brain regions. The results also lend support to the idea that this separation allows the creation of separable, non-interfering motor memories.

Acknowledgments: NSERC, MITACS