Neuronal Representations Supporting Three-Dimensional Vision in Nonhuman Primates.

The visual system must reconstruct the dynamic, three-dimensional (3D) world from ambiguous two-dimensional (2D) retinal images. In this review, we synthesize current literature on how the visual system of nonhuman primates performs this transformation through multiple channels within the classically defined dorsal (where) and ventral (what) pathways. Each of these channels is specialized for processing different 3D features (e.g., the shape, orientation, or motion of objects, or the larger scene structure). Despite the common goal of 3D reconstruction, neurocomputational differences between the channels impose distinct information-limiting constraints on perception. Convergent evidence further points to the little-studied area V3A as a potential branchpoint from which multiple 3D-fugal processing channels diverge. We speculate that the expansion of V3A in humans may have supported the emergence of advanced 3D spatial reasoning skills. Lastly, we discuss future directions for exploring 3D information transmission across brain areas and experimental approaches that can further advance the understanding of 3D vision.