Orientation preference and horizontal disparity sensitivity in the monkey visual cortex

PURPOSE: Disparity sensitivity may be explained by interocular positional differences of the receptive fields (RF) of visual cortical cells or by interocular shifts of the On and Off RF subregions. Since this latter model assumes shifts are orthogonal to the orientation of the RF, cells with disparity sensitivity should be oriented. The objective of the present study is to test this assumption. METHODS: Single unit recordings were performed in areas V1 and V2 of two Macaca mulatta. For assessing disparity sensitivity, we generated dynamic random dot stereograms. A stereofigure was flashed over the cell RF with different horizontal disparities. To assess orientation sensitivity we used a flashing bar with eight orientations, in several positions over the cell RF in a pseudorandom manner. RESULTS: We found no relationship between sensitivity to horizontal disparity and orientation preference in V1 and V2 cells. CONCLUSIONS: Our data indicate that horizontal disparity sensitivity and orientation preference are unrelated properties. This favors the notion that sensitivity to horizontal disparity is mostly based on RF interocular horizontal positional differences.

Publication year:2010