Responses of extrastriate cortex to switching perception of ambiguous visual motion stimuli.

We recently found that in bistable apparent motion (AM) both the motion complex (hMT/V5+) and kinetic occipital area (KO) transiently activated whenever perception switched in the spinning wheel illusion. Here, we tested the specificity of this result with another bistable AM stimulus, the dynamic dot quartet, that does not involve kinetic contours. We observed significant activations in hMT/V5+, but not in KO. This indicates that neural activity in functionally specialized extrastriate visual areas during switching perception of ambiguous input depends on stimulus features in a finely tuned way suitable to encode perceptual content in the absence of sensory input changes.