• human visual cortex
• population receptive field
• psychophysics
• fMRI
• stereopsis
• random dot stereograms
• binocular disparity
• pedestal depth

The neural processing of binocular disparity is one of the main mechanisms allowing three-dimensional (3D) vision in humans, and it takes place in the cerebral cortex. By using functional Magnetic Resonance Imaging (fMRI), it is possible to model neuronal receptive fields averaged over a population of the order of hundreds of thousands of neurons (population receptive field, pRF). The aim of this project was therefore to characterize disparity pRFs organization and response properties, i.e. the variability in tuning curve profiles, regarding in particular the nature of the response (tuned/categorical) and tuning width, in most visual areas currently known (V1, V2, V3, V4, VOC, LO1-2, V3A-B, TO1-2, V7), and assess how they relate to depth perception.
We found that disparity pRFs are organized in accordance with the Weber-Fechner law, for both correlated and anticorrelated disparity stimuli. In the first case, however, we estimated significantly smaller Weber fractions in almost all areas. We also report that pRF tuning width in areas VOC and V3AB is a strong predictor of perceptual stereoacuity threshold.