Figure 1.

Center-out/out-center reaching task. a, Monkey moved a cursor (yellow ball), controlled by an optical marker on the hand, to hit a target (blue ball) in a virtual environment. Occasionally, between trials, the monkey would spontaneously rest its hand on the lap plate (black arrow). b, Continuous trial timeline, consisting of IR, IH, FR, FH, and IT, and then starting over from IR again. The color code defined by this diagram is used to indicate the respective task periods throughout all figures, unless otherwise indicated. The two Reach periods are the same color and so are the two Hold periods, because these periods are pooled in the subsequent analyses. c, Hand trajectories from successful trial periods (IH thru FH), and d, IT periods for one entire Monkey F session, color coded by task period. The hand trajectories were in 3D space, but only projections onto the x–y plane are shown.