Postural context alters the stability of bimanual coordination by modulating the crossed excitability of corticospinal pathways.

The tendency for movements of the upper limbs to be drawn systematically toward one another and to follow similar spatiotemporal trajectories is well known. Although suppression of this tendency is integral to tasks of daily living, its exploitation may prove to be critical in the rehabilitation of acquired hemiplegias. In general, however, the task-related factors that determine the degree of coupling between the upper limbs and the mechanisms that mediate bilateral interactions between neural pathways projecting to the muscles of the arm and hand are not yet well understood.

The effect of volition on the stability of bimanual coordination.

The authors investigated how the intention to passively perform a behavior and the intention to persist with a behavior impact upon the spatial and temporal properties of bimanual coordination. Participants (N = 30) were asked to perform a bimanual coordination task that demanded the continuous rhythmic extension-flexion of the wrists. The frequency of movement was scaled by an auditory metronome beat from 1.