Pattern motion and component motion sensitivity in cat superior colliculus.

Single neurons in the superior colliculus of the cat were tested for their direction-tuning responses to random-line patterns composed of identical short lines moving obliquely to their common orientation. A substantial population of cells responded primarily to the veridical direction of pattern motion while a few were sensitive to the orientation of component lines. Moreover, for most cells, the pattern motion sensitivity decreased when the orientation element was enhanced by elongating the component lines in stimulus. Further analysis found that the initial transient responses after stimulus onset were relatively more sensitive to component motion than the subsequent sustained responses. These findings suggest that the superior colliculus is involved in the higher-order analysis of visual motion so that collicular neurons can signal coherent pattern motion in many cases.