Perinatal correlated retinal activity is required for the wiring of visual axons in non-image forming nuclei

The formation of the visual system is a complex multistep process that includes the establishment of proper connectivity of retinal ganglion cell (RGC) axon terminals with their relay neurons located in the brain. In mammals, the assembly of the different components of the visual circuit occurs at perinatal stages before eye opening. Upon reaching the target nuclei RGC axons extensively arborize and subsequently refine to establish the final connections. Spontaneous activity generated in the immature retina plays an essential role in the refinement of visual terminals at the main image-forming nuclei (IFN) that follow an eye-specific and retinotopic organization. However, the molecular mechanisms underlying spontaneous activity-dependent axon remodeling, and the influence of this activity in the connectivity of non-image forming nuclei (NIFN) that lack precise retinotopic maps and/or eye-specific segregation, are not well known. Here, by generating conditional mice with disturbed spontaneous retinal aneactivity and analyzing their retinal transcriptomic profiles, we identified novel players involved in axon refinement at the visual nuclei (e. g. Syt13). The analysis of visual projections in the NIFN of these mice revealed that correlated-retinal activity shapes final connectivity in non retinotopic or eye-specific segregating visual nuclei.