High-field imaging of depth perception.

The binocular disparity between the views of the world registered by the left and right eyes provides a powerful signal about the depth structure of the environment. Despite increasing knowledge of the cortical areas that process disparity from animal models, comparatively little is known about the local architecture of stereoscopic processing in the human brain. We take advantage of the high spatial specificity and image contrast offered by ultra-high-field (7-tesla) functional imaging to test for systematic organization of disparity representations in the human brain. Participants viewed random dot stereogram stimuli depicting different depth positions while we recorded fMRI responses from a slab of voxels covering dorsomedial visual cortex. We show that disparity preferences are clustered, and this organization persists across imaging sessions, particularly in area V3A. Our findings indicate that human dorsal visual cortex contains selective cortical structures for disparity that are likely to be important for stereoscopic depth processing.