Geometry representations along visual pathways in human spatial navigation
The representation of geometric structures in the environments is key to self-localization during human spatial navigation. Its spatial organization in the visual system is not fully characterized. Using brain activity from 20 participants watching videos from identical realistic virtual environments under different weather and lighting conditions, we found a compact representation of scene geometric structures encoded in a large network of brain regions, allowing for reconstructing depth. It forms a continuous map composed of three parallel pathways that we jointly coin as "geometry visual pathways", starting from the primary visual cortex: the dorsal and medial pathways end in the intraparietal areas, while the ventral pathway arrives at the hippocampus via the parahippocampal gyrus. Furthermore, road types, a more abstract representation of geometry, are encoded in overlapping pathways excluding early visual cortex (V1, V2, V3). The geometry visual pathways provide new insights into the traditional dichotomy between "what" and "where" pathways.