Comparing neuronal and behavioral thresholds for spiral motion discrimination.

As we move, the projection of moving objects on our retinas generates an array of velocity vectors known as optic flow. One class of optic flow is spiral motion, defined by the angle between a local vector direction and the direction of the steepest increase in local speed. By discriminating among such angles, an organism could discern between different flow patterns and effectively interact with the environment. In primates, spiral-selective neurons in medial superior temporal area are thought to provide the substrate for this ability. We found that these cells show higher discrimination thresholds than found behaviorally in humans, suggesting that when discriminating spiral motions the brain integrates information across many of these neurons to achieve its high perceptual performance.