Neural correlates of structure-from-motion perception in macaque V1

Structure-from-motion (SFM) is the perception of three-dimensional shape from motion cues. We used a bistable SFM stimulus, which can be perceived in one of two different ways, to study how neural activity in cortical areas V1 and MT is related to SFM perception. Monkeys performed a depth-order task, where they indicated in which direction the front surface of a rotating SFM cylinder display was moving. To prevent con-tamination of the neural data because of eye position effects, all experiments with significant effects of radius, vergence, and velocity were excluded. As expected, the activity of 50 % of neurons in V1 and 80 % of neurons in MT is affected by the stimulus. Furthermore, the activity of 20 % of neurons in area V1 is modulated with the percept. This proportion is higher in MT, where the activity of 60 % of neurons is modulated with the percept. In both areas, this perceptual modulation occurs onl