A neural representation of depth from motion parallax in macaque visual cortex

Depth perception in humans and other animals can be based on binocular vision, in which the brain compares images from each eye. We can also judge depth with one eye, but how the brain processes the many different cues available for monocular perception of depth is not known. A possible explanation for one cue has now been found. The neurons in the middle temporal area of the brain, as well as representing retinal motion, can combine visual information and physical movement to extract depth information from motion parallax, a powerful depth cue that we experience when viewing the scenery from the window of a moving train — objects on the horizon move slowly while the scene close to the train flashes by.