Fig. 3.

Movement trajectories, aiming errors, and learning indices from 2 typical subjects during the adaptation set of a single experimental session. A: healthy control subject (C05; Table 1); B: cerebellar subject (P19; Table 1). Left: movement trajectories early and late in adaptation. Dashed lines represent movement trajectories of the first 12 movements in the set, and solid lines represent movement trajectories of the last 12 movements in the set. The target locations are depicted by white circles. Middle: aiming errors (AE; degrees) of perturbed trials and catch trials corresponding to the same set of the movement trajectories. Solid lines represent the average aiming error during force-field trials. Aiming errors were averaged over bins of 6 trials. Stars represent the aiming error of catch trials. When a subject adapts to the force field, the average aiming error will decrease, and catch trials will show increasing errors in the opposite direction of the force. Right: learning index (LI) during the force-field set. The learning index was calculated over bins of 6 perturbed trials and 1 catch trial. Solid lines represent the average learning index during adaptation. Shaded areas of the plot represent the bins over which the final learning index was calculated (last 6 bins).