Re-evaluating the Role of Intrinsically Photosensitive Retinal Ganglion Cells: New Roles in Image-Forming Functions

Recently, researchers identified a novel ganglion cell photoreceptor in vertebrates, called intrinsically photosensitive retinal ganglion cells (ipRGCs). These ipRGCs are photosensitive due to expression of a photopigment, melanopsin. Although ipRGCs were initially thought to be a uniform population of cells involved solely in subconscious, non-image forming behaviors, recent research points to a role for ipRGCs in pattern vision. Here we highlight the emerging evidence for this influence of ipRGCs on pattern vision and discuss important future directions for understanding this newly appreciated contribution of melanopsin signaling to visual processing.