Figure 1.

Experimental setup and heading trajectories. A, Schematic illustration of the virtual reality apparatus. The monkey, field coil, projector, and screen were mounted on a motion platform that can translate in any direction in 3D. B, On each trial, the monkey was required to fixate one of three possible targets along the horizontal meridian, separated by 20, 22.5, or 25° of visual angle. C, Illustration of the 26 movement trajectories used to measure heading tuning in the 3D experiments. All movements originated from the center position and had a Gaussian velocity profile (total displacement, 13 cm; duration, 2 s). D, Illustration of the 10 trajectories tested in the 2D (horizontal plane) experiments.