Mammalian Inner Retinal Photoreception

It is now a decade since the first published reports that a small proportion of mammalian retinal ganglion cells are directly photoresponsive. These cells have been termed intrinsically photosensitive retinal ganglion cells (ipRGCs) and comprise a small proportion of the total population of retinal ganglion cells. The demonstration that these ganglion cells respond to light even when isolated from the rest of the retina established them as potentially autonomous photoreceptors, overturning the dogma that all visual information originates with rods and cones. It also provided a focus for what has developed into a new branch of visual science. Here we place the discovery of ipRGCs into context and review the development of this field over the last decade, with particular emphasis on prospects for practical application.