How the Brain Escapes the Flat-Screen World to See in 3D

While much research has treated vision as if we see a flat, 2D canvas, our survival has always depended on navigating a complex 3D world. New findings are showing how the visual systems of mammals are exquisitely adapted for this task.

The key lies in neurons sensitive to binocular disparities—the subtle differences between the input each eye receives. By calculating these disparities, the visual cortex constructs our sense of depth. This mechanism, well-known in primates, has now been characterised in species like tree shrews and mice.

Further along the visual processing chain, the brain uses two specialised pathways. The ventral ('what') pathway recognises complex 3D objects by their geometric parts. Meanwhile, the dorsal ('where'/'how') pathway represents an object's position and orientation, providing a stable perception for action, regardless of where our gaze falls.

Understanding this sophisticated neural organisation for 3D experience is essential for advancing our knowledge of cognition and behaviour, and for developing future therapies for visual impairments.