The functional organisation of retrosplenial feedback to V1

Cortical feedback from higher frontal and association areas to early sensory cortex is thought to contribute to a range of cognitive processes in which sensory signals are processed in a context sensitive manner. Despite the ubiquity of feedback circuitry in the cortex, the information carried by feedback connections, and the principles governing how it is targeted from area to area remains poorly understood. Here we characterized the functional properties of a prominent feedback circuit which links retrosplenial cortex (RSC) and primary visual cortex (V1). We found that RSC→V1 axons relay retinotopically selective signals to V1 which at a coarse scale match the region of the V1 retinotopic map innervated, were tuned for spatial and temporal frequency, but not tuned for orientation. Two-color imaging of RSC→V1 boutons and local L2/3 V1 neurons further revealed that at a finer scale RSC→V1 bouton receptive fields are systematically offset relative to those of V1 in the nasal direction, consistent with RSC→V1 boutons conveying signals predictive of upcoming V1 activity in the retinotopic region innervated during forward movement.