Human cortical area responding to stimuli in apparent motion.

Apparent motion is the perception of the realistic smooth motion of an object which flashes first at one place then at another. To investigate human cortical responses to stimuli in apparent motion, we used a multichannel biomagnetometer to record the magnetic fields evoked by these stimuli in four normal subjects. The results showed the presence of a localized cortical area exclusively sensitive to apparent motion stimuli that is identical to that for smooth motion. In three subjects this area corresponded to the human homologue of MT/V5. Moreover, the same region in the extrastriate cortex was involved in the short range (0.1 degree) apparent motion process as well as the long range (1.0 degree) process.