A theory of subicular function and generalized vector coding

Located in the hippocampal formation, the subiculum exhibits numerous, seemingly unrelated neural codes, without a common account of neuronal selectivity. We propose Disco, a theory that can explain activity in the subiculum and related neural codes in other areas. Given the continuous flow of experience, subicular activity can be understood as signalling discontinuities in that flow, coded in a vector-base. Geometric discontinuities drive responses to walls, drops, objects, holes, corners and curved surfaces. The generality of Disco enables predictions for 3D environments, natural scenes, and mixed-modality coding. Non-spatial discontinuities in behavioral state yield axis-coding, and tracking population activity signals event boundaries as temporal discontinuities. The ability to generate this diverse set of neural activity suggests that discontinuity coding is a key principle underlying subicular activity.