Figure 1.

Center-out with rotation task and hand kinematics. The subject's 3D hand position and hand orientation in the frontal plane were mapped directly to the position and orientation of the orange cursor in the virtual reality simulator. A, The subject started each movement from a center target with vertical orientation. B, In this example, the subject reached for a target at the forward, upper, and right corner of the workspace with clockwise rotation of the hand. C, The monkey captured the target. D, E, Average 3D hand trajectory and hand orientation in the frontal plane for eight peripheral targets with counterclockwise and clockwise rotation, respectively. Position of the black dots represents the instantaneous 3D hand position. Orientation of the small red vertical lines indicates hand orientation in the frontal plane at four time points: start of movement, one-third into movement, two-thirds into movement, and end of movement (length of the small vertical line is arbitrary). At the time points corresponding to start and end of movement, blue “+” signs were plotted to indicate the horizontal and vertical directions to facilitate the visualization of hand rotation. Hand kinematics was also plotted as a function of time in supplemental Figure 8 (available at www.jneurosci.org as supplemental material). Note that hand translation and rotation occurred simultaneously, as further demonstrated by supplemental Figures 1 and 2 (available at www.jneurosci.org as supplemental material).