Fig. 1.

Sequence of visual cues. A) In inter-trial intervals the arms were relaxed and the red cursor bars indicating the grip force registered by the dynamometers were down at the bottom of the white vertical bars. B) At the start of each trial, a white dot and a red horizontal bar appeared either behind the left or the right white bar corresponding to the left and right hand respectively. The cue displayed here instructs patients to grip with their right hand at the lightest level (15% of maximum sustainable force). C) Patients adjusted their grip force such that the red vertical column rises to the same level of the red horizontal bar. D) Example of a trial instructing gripping at the strongest level (85% of maximum sustainable force) with the left hand. In the imagined condition, the red horizontal cues indicate the force level and effector side as during real gripping, however the red vertical bar remained down.