The physiology of stereopsis

Binocular disparity provides the visual system with information concerning the three-dimensional layout of the environment. Recent physiological studi es in the primary visual cortex provide a successful account of the mechani sms by which single neurons are able to signal disparity. This work also re veals that additional processing is required to make explicit the types of signal required for depth perception (such as the ability to match features correctly between the two monocular images). Some of these signals, such a s those encoding relative disparity, are found in extrastriate cortex. Seve ral other lines of evidence also suggest that the link between perception a nd neuronal activity is stronger in extrastriate cortex (especially MT) tha n in the primary visual cortex.