Post-developmental plasticity of the primary rod pathway allows restoration of visually guided behaviors.

The formation of neural circuits occurs in a programmed fashion, but proper activity in the circuit is essential for refining the organization necessary for driving complex behavioral tasks. In the retina, sensory deprivation during the critical period of development is well known to perturb the organization of the visual circuit making the animals unable to use vision for behavior. However, the extent of plasticity, molecular factors involved, and malleability of individual channels in the circuit to manipulations outside of the critical period are not well understood. In this study, we selectively disconnected and reconnected rod photoreceptors in mature animals after completion of the retina circuit development. We found that introducing synaptic rod photoreceptor input post-developmentally allowed their integration into the circuit both anatomically and functionally. Remarkably, adult mice with newly integrated rod photoreceptors gained high-sensitivity vision, even when it was absent from birth. These observations reveal plasticity of the retina circuit organization after closure of the critical period and encourage the development of vision restoration strategies for congenital blinding disorders. [Display omitted] • Cell adhesion molecule Elfn1 is essential for maintenance of rod synapses • Reactivation of Elfn1 expression in adult mice allows rods to form synapses • Post-developmentally rescued rod synapses are functional • Mice gain dim-light vision upon restoration of rod connectivity in adult retinas Cao et al. examine the mechanisms that govern post-developmental connectivity of rod photoreceptors into the retinal circuitry. This study reports that rod synapse formation can be restored in adult mice, enabling their rod-mediated vision at the behavioral level. [ABSTRACT FROM AUTHOR]