Mouse visual cortex contains a region of enhanced spatial resolution

Abstract

The representation of space in mouse visual cortex was initially thought to be relatively uniform, with no strong biases towards any particular region of space. This contrasts with the primate visual cortex with its over-representation of the fovea, placing potential limits on the translation of research in mice to humans. Here we reveal a previously unsuspected organization of the visual cortex of mice that resembles that fovea-centric organization of human visual cortex. Using population receptive-field (pRF) mapping techniques, which allow estimates to be made of aggregate receptive field sizes, we found that mouse visual cortex contains a region in which pRFs are considerably smaller. This region, the ‘focea’, represents a location in space directly in front of, and slightly above, the mouse. Using two-photon imaging we show that the smaller pRFs are due to a more orderly representation of space and an over-representation of binocular regions of the visual scene. We also show that RFs of single neurons in areas LM, AL and AM are smaller at the focea. Mice have improved visual resolution in this region of space and freely-moving mice make compensatory eye-movements to hold this region in front of them. Our results indicate that the representation of space in mouse visual cortex is non-uniform and mice have spatial biases in their visual processing. The presence of a focea has important implications for the use of the mouse model of vision.