Independent Encoding of Orientation and Mean Luminance by Mouse Visual Cortex.

Natural environments contain behaviorally relevant information along many stimulus dimensions, each of which sensory systems must encode in order to guide behaviors. For example, the mammalian visual cortex encodes features of visual scenes such as spatial information related to object identity and temporal information about the motion of those objects in space. In order to reliably encode these behaviorally relevant visual features, neural representations should be robust to changes in environmental conditions. Further, information about changes in environmental conditions, such as the luminance changes that occur over the course of a day, is also important for guiding behaviors. In this study, we asked whether mouse primary visual cortex (V1) jointly represents the spatial properties of visual stimuli along with changes in the mean luminance of the visual scene. We find that while V1 neurons, in mice of either sex, encode spatial aspects of visual information in an invariant manner across luminance conditions, the V1 population response also contains a robust representation of luminance. Importantly, V1 populations encode changes in stimulus orientation and mean luminance along orthogonal axes in the neural response space, such that a change in one stimulus variable is encoded independently from the other.