Light acts through melanopsin to alter retinal waves and segregation of retinogeniculate afferents.

Waves of correlated activity sweeping across the early postnatal mouse retina promote the segregation and refinement of retinofugal projections. This process has been thought to be spontaneous and unaffected by visual experience. We found, however, that light prolongs spiking during the waves and enhances the segregation of retinogeniculate afferents, and that it did so by activating melanopsin-expressing, intrinsically photosensitive retinal ganglion cells.