ON/OFF domains shape receptive fields in mouse visual cortex

In higher mammals, thalamic afferents to primary visual cortex (area V1) segregate according to their responses to increases (ON) or decreases (OFF) in luminance. This organization induces columnar, ON/OFF domains postulated to provide a scaffold for the emergence of orientation tuning. To further test this idea, we asked whether ON/OFF domains exist in mouse V1 -- a species containing orientation tuned, simple cells, like those found in other mammals. Here we show that mouse V1 is indeed parceled into ON/OFF domains. Revealingly, fluctuations in the relative density ON/OFF neurons on the cortical surface mirror fluctuations in the relative density of ON/OFF receptive field centers on the visual field. In each cortical volume examined, the average of simple-cell receptive fields correlates with the difference between the average of ON and OFF receptive fields. Moreover, the local diversity of simple-cell receptive fields is explained by a model in which neurons linearly combine a small number of ON and OFF signals available in their cortical neighborhoods. Altogether, these findings indicate that ON/OFF domains originate in fluctuations of the spatial density of ON/OFF inputs on the visual field which, in turn, shapes the structure of receptive fields.