CONTOUR FROM MOTION PROCESSING OCCURS IN PRIMARY VISUAL-CORTEX

RELATIVE motion is one of the most salient cues for segmentation of a visual scene into separate objects. This is illustrated by the vivid c ontours that are perceived when random dot patterns move in different directions1,2. Once motion is hatted in such displays the segmentation contours disappear. This makes random dot patterns ideal for the stud y of contour from motion processing in isolation. Contour from motion processing obviously relies on direction-selective neurons, which are found in many visual cortical areas3-5. It is, however, largely unknow n at what level of processing their signals interact to serve the glob al process of motion-based image segmentation. To answer this quesion, we recorded visually evoked potentials, both in man and in awake monk ey, to a stimulus specifically designed to signal the presence of neur onal activity related to contour from motion processing. We report her e that response components specific to contour from motion were elicit ed only when the stimulus yielded a contour percept. In awake monkey, the sources of these components were located within the supra- and inf ra-granular layers of primary visual cortex. We conclude that V1 is in volved in image segmentation processing.