Disparity sensitivity in the superior colliculus of the cat

The present study aims at evaluating the spatial disparity response profiles of binocular cells in the superficial layers of the superior colliculus of the cat using drifting light bars and phase-shifted spatial frequency gratings. Results show that a total of 64% of the cells were sensitive to phase disparities and had large tuning profiles. Similarly, a large proportion (75%) of those tested with position offsets showed one of the four classic disparity profiles, those of the tuned cells being rather coarse. When tested with both position and phase disparities, 54% of the cells showed sensitivity profiles to the two types of stimuli. The overall results suggest that the superior colliculus is involved in the analysis of coarse stereopsis and/or the planning and initiation of saccades during vergence eye movements and/or the control of fine adjustments to maintain fixation as the stimulus moves in depth.