Neural substrate for a high degree of noise tolerance in visual flow discrimination in macaque dorsal MST area

To reveal the underlying cellular mechanisms of the noise tolerance in the discrimination of the direction of visual flow, we analyzed both response behaviors of directionally selective cells in the d-MST of the macaque and discrimination properties of human subjects for visual flow by using large-field texture flow. The stimulus was a 32×32-pixel random checker pattern refreshed at every 16 msec in which coherency of the motion of the texture was systematically controlled by a special purpose computer. The discrimination performance of the human observers showed a high degree of tolerance for directional noise. Field-type D-cells in d-MST also showed response properties which closely resembled human discrimination performance. These results strongly suggest that cells in d-MST area play a crucial role in the generation of signals for perception of global motion.