Linking neural representation to function in stereoscopic depth perception

Although binocular disparity signals have been indentified in several cortical visual areas in primates, the respective roles of these different areas in stereopsis remain poorly understood. I will summarize some of our recent efforts to characterize the roles that visual area MT plays in depth perception. I will describe single-unit recording and microstimulation experiments which show that MT plays an important role in coarse judgments of depth from absolute disparities, whereas it appears not to contribute to fine judgments of relative depth. In addition, I will show that this task-specific contribution of MT can be simply explained by the fact that MT neurons code absolute, but not relative, disparities, the latter of which are necessary for fine depth discrimination. These results establish an important link between neural representation and function.