Intermediate level cortical areas and the multiple roles of area V4

Despite advances in deep neural networks for object recognition, the function of the mid-level stages of visual processing in the mammalian cortex evades a simple description. This review focuses on the status of cortical area V4 to present evidence for a diversity of roles for mid-level visual areas. Some properties of V4 neurons resemble the static nature of mid-layers of neural networks when training has been completed. However, V4 also gates information flow to higher cortical areas in a dynamic way, reflecting the influences of attention, context, and reward. The most recent evidence suggests a role for mid-level cortical areas in the selective generation of responses to specific sensory inputs. The finding of signals relating to response selection in cortical areas whose role was thought to be fundamentally concerned with sensory representations will require a different approach to evaluating the roles of these areas in cognition.