Static representations of speed and their neural correlates in human area MT/V5.

Studies have shown that cortical area MT/V5 is activated by visual motion as well as illusory motion, implied motion in static images, or motion imagery. Cells within these areas are additionally tuned for speed and exhibit different responses depending on the actual speed of an object. In this study, we investigate the relationship between perceived speed as represented within static images and the patterns of activity observed in MT/V5. Consistent with other studies, we show robust responses in MT/V5 to implied motion. In addition, our results show an increase in the blood-oxygen level dependent response consistent with the increased speed information inherent within the images. In the absence of any real physical motion, the data illustrate the intricate manner in which top-down activity influences visual cortical activity.