Neural maps versus salt-and-pepper organization in visual cortex

•Evolution: does size matter?•Dynamical factors shaping the layout of visual response properties.•The role of patterned visual input in development and the issue of stability.•Staying selective in a heterogeneous network.•Impact of map layout on visual processing?

Theoretical neuroscientists have long been intrigued by the spatial patterns of neuronal selectivities observed in the visual cortices of many mammals, including primates. While theoretical studies have contributed significantly to our understanding of how the brain learns to see, recent experimental discoveries of the spatial irregularity of visual response properties in the rodent visual cortex have prompted new questions about the origin and functional significance of cortical maps. Characterizing the marked differences of cortical design principles among species and comparing them may provide us with a deeper understanding of primate and non-primate vision.