Neural correlates associated with intermanual transfer of sensorimotor adaptation.

Investigations of intermanual transfer of learning have demonstrated that individuals can transfer acquired motor skills from one hand to the other. The purpose of the current study was to use fMRI to investigate the potential overlap of neural regions engaged during learning and at transfer of learning from the dominant arm to the non-dominant arm during sensorimotor adaptation. Participants performed a visuomotor adaptation joystick task where they adapted manual aiming movements to a 30 degrees rotation of the visual feedback display. They performed eleven blocks (24 trials/block) of right-hand adaptation before performing the task with their left hand (transfer). Participants showed a selective transfer of learning effect: prior right-hand practice led to reduced endpoint errors but not trajectory errors for the left hand. This is consistent with work showing that the right arm is specialized for trajectory control while the left is specialized for endpoint control [Sainburg, R.L., 2005. Handedness, Differential specializations for control of trajectory and position. Exerc Sport Sci Rev 33, 206-213.]. Early adaptation processes were associated with activation in frontal and parietal regions, including bilateral dorsal premotor cortex. At transfer, activation was seen in the temporal cortex as well as the right medial frontal gyrus and the middle occipital gyrus. These regions have been observed in other studies during the late phases of sensorimotor adaptation. Integrating these data with the existing literature, we suggest that the left dorsal premotor cortex contributes to trajectory control, while the left visual and temporal cortices contribute to endpoint control.