The ON-OFF directionally selective cells of the retina respond preferentially to movement in a preferred direction, but under laboratory conditions they are also sensitive to changes in the luminance of the stationary stimulus. If the response of these neurons contains information about both direction and luminance downstream neurons are faced with the challenge of extracting the motion component, a computation that may be difficult under certain viewing conditions. Here, we show that during natural viewing the response to luminance is suppressed, leaving a relatively pure motion signal that gets transmitted to the brain
