Figure 1.

Experimental apparatus and tasks. A, Experimental apparatus. Monkeys, starting from a central position (C), performed direct reaches (toward A) or made hand movement corrections of 180° (from A to B) to peripheral targets arranged at the vertices of a virtual cube. In the CorR trials, the hand path originally directed to the first target location (A) reverses toward the new location (B) after the target “jump” occurring during the RT. B, Temporal structure of DirR and CorR trials. Gray horizontal bars indicate the duration of presentation of visual targets; black curves represent hand position in parametric form for a generic coordinate x_i(t). For the CorR trial, the hand position is also shown (gray line) in the absence of a target jump (DirR) for a direct comparison of the two movement conditions.