Patterns of Ocular Dominance are in the Eye of the Beholder

Ocular Dominance Columns (ODCs), structures in the early visual cortex that demarcate inputs from each eye, have been observed in a wide range of mammals. The extent and arrangement of these columnar structures can vary drastically from species to species, and even along the visual cortex of a single individual. While previous studies show that these structures can form by competitive Hebbian learning, the relationship between system parameters and the resulting organizational patterns remains unclear. Here, we use a mesoscopic model of V1 development to explain how the different observed patterns of ocular dominance (columns, islands, and monocular) can arise through local Hebbian competition, as a function of the density of projections from each eye and cortical interaction strengths. We argue that our results explain the broad cortical organizational differences between species which have forward-facing versus steeply angled eyes. We additionally show that spatially varying retinal input projections, which can arise from a combination of retinotopy and varying cell density, can lead to coexistence of multiple ocular dominance patterns along the cortical sheet, consistent with experimental observations.