(Medical Xpress) — Remarkably, cortical maps show that neurons in the primary visual cortex have specific preferences for the location and orientation of a given visual field stimulus but how these maps develop and what function they play in visual processing remains a mystery. Evidence suggests that the retinotopic map is established by molecular gradients, but little is known about how orientation maps are wired. One hypothesis: at their inception, these orientation maps are seeded by the spatial interference of ON- and OFF-center retinal receptive field mosaics. Recently, scientists in the Departments of Neurobiology and Psychology at the University of California, Los Angeles have shown that this proposed mechanism predicts a link between the layout of orientation preferences around singularities of different signs and the cardinal axes of the retinotopic map, and have confirmed this prediction in the tree shrew primary visual cortex. The researchers say their findings support the idea that spatially structured retinal input may provide a blueprint of sorts for the early development of cortical maps and receptive fields and that the same may hold true for other senses as well.