Efficient Receptive Field Tiling in Primate V1

•Spatial frequency and ocular dominance maps have parallel gradients in macaque V1•Map regions encoding higher spatial frequencies align with binocular zones•Retinotopy is extremely precise when zooming into the maps with two-photon imaging•Smooth micro-retinotopy requires efficient alignment of feature maps for full coverage

SummaryThe primary visual cortex (V1) encodes a diverse set of visual features, including orientation, ocular dominance (OD), and spatial frequency (SF), whose joint organization must be precisely structured to optimize coverage within the retinotopic map. Prior experiments have only identified efficient coverage based on orthogonal maps. Here we used two-photon calcium imaging to reveal an alternative arrangement for OD and SF maps in macaque V1; their gradients run parallel but with unique spatial periods, whereby low-SF regions coincide with monocular regions. Next we mapped receptive fields and found surprisingly precise micro-retinotopy that yields a smaller point-image and requires more efficient inter-map geometry, thus underscoring the significance of map relationships. While smooth retinotopy is constraining, studies suggest that it improves both wiring economy and the V1 population code read downstream. Altogether, these data indicate that connectivity within V1 is finely tuned and precise at the level of individual neurons.