Representation of binocular surfaces by cortical neurons.

Useful representations of the three-dimensional (3D) world go beyond assigning depth to individual points, building maps of surfaces and shapes. Studies in a wide range of extrastriate cortical areas have shown that single neurons show selective responses to 3D surfaces. The extent to which this advances the representation beyond that provided by the earliest binocular signals requires careful evaluation. We conclude that current data are not sufficient to identify distinctive contributions from different cortical areas to the binocular representation of 3D surfaces.