RT Journal Article
SR Electronic
T1 Emergence of Lamina-Specific Retinal Ganglion Cell Connectivity by Axon Arbor Retraction and Synapse Elimination
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 16376
OP 16382
DO 10.1523/JNEUROSCI.3455-10.2010
VO 30
IS 48
A1 Ting-Wen Cheng
A1 Xiao-Bo Liu
A1 Regina L. Faulkner
A1 Alexander H. Stephan
A1 Ben A. Barres
A1 Andrew D. Huberman
A1 Hwai-Jong Cheng
YR 2010
UL http://www.jneurosci.org/content/30/48/16376.abstract
AB Throughout the nervous system, neurons restrict their connections to specific depths or “layers” of their targets to constrain the type and number of synapses they make. Despite the importance of lamina-specific synaptic connectivity, the mechanisms that give rise to this feature in mammals remain poorly understood. Here we examined the cellular events underlying the formation of lamina-specific retinal ganglion cell (RGC) axonal projections to the superior colliculus (SC) of the mouse. By combining a genetically encoded marker of a defined RGC subtype (OFF-αRGCs) with serial immunoelectron microscopy, we resolved the ultrastructure of axon terminals fated for laminar stabilization versus those fated for removal. We found that OFF-αRGCs form synapses across the full depth of the retinorecipient SC before undergoing lamina-specific arbor retraction and synapse elimination to arrive at their mature, restricted pattern of connectivity. Interestingly, we did not observe evidence of axon degeneration or glia-induced synapse engulfment during this process. These findings indicate that lamina-specific visual connections are generated through the selective stabilization of correctly targeted axon arbors and suggest that the decision to maintain or eliminate an axonal projection reflects the molecular compatibility of presynaptic and postsynaptic neurons at a given laminar depth.