CELL RESPONSES TO VERTICAL AND HORIZONTAL RETINAL DISPARITIES IN THE MONKEY VISUAL-CORTEX

Because of the horizontal separation of both ocular globes, the projec tion angles are slightly different. These differences are commonly ter med retinal disparities. Vertical and horizontal retinal disparities o ccur constantly in normal life. We have investigated the responses of single cells in cortical areas V1 and V2 of behaving Macaca mulatta mo nkeys to retinal disparities by using dynamic random dot stereograms. Our findings show that cortical visual cells are sensitive to both ver tical and horizontal disparities. To calculate the distance between tw o objects in a three-dimensional space from horizontal disparities, it is necessary to know the fixation distance. It has been suggested tha t the horizontal gradient of vertical disparity contains information t o estimate the fixation distance and therefore to scale horizontal dis parities. We suggest that these cells sensitive to horizontal and vert ical disparities represent a neural mechanism that provides informatio n to the visual system in order to achieve a correct eye alignment and depth perception.