BINOCULAR DISPARITY DISCRIMINATION IN HUMAN CEREBRAL-CORTEX - FUNCTIONAL-ANATOMY BY POSITRON EMISSION TOMOGRAPHY

Neurobiological studies in higher primates indicate that the processin g of stereoscopic information takes place at early levels in the visua l cortex. To map the anatomical structures in the human brain particip ating in pure stereopsis based upon binocular disparity, we measured w ith positron emission tomography the changes in regional cerebral bloo d flow as an indicator of metabolic activity in 10 healthy young men d uring visual discrimination of binocular disparity. The data demonstra te that the discrimination of pure stereoptic disparity information ta kes place in the polar striate cortex and the neighboring peristriate cortices, as well as in the parietal lobe, the prefrontal cortex, and the cerebellum. The discrimination of stereoscopic depth is dependent on a network composed of multiple functional fields localized in occip ital- and parietal-lobe visual areas as well as in the dorsolateral an d mesial prefrontal cortex. The findings support the importance of coa ctivated occipitoparietal visual areas in the processing and analysis of binocular depth information in humans.