Developmental mechanisms that regulate retinal ganglion cell dendritic morphology

Abstract

One of the fundamental features of retinal ganglion cells (RGCs) is that dendrites of individual RGCs are confined to one or a few narrow strata within the inner plexiform layer (IPL), and each RGC synapses only with a small group of presynaptic bipolar and amacrine cells with axons/dendrites ramified in the same strata to process distinct visual features. The underlying mechanisms which control the development of this laminar-restricted distribution pattern of RGC dendrites have been extensively studied, and it is still an open question whether the dendritic pattern of RGCs is determined by molecular cues or by activity-dependent refinement. Accumulating evidence suggests that both molecular cues and activity-dependent refinement might regulate RGC dendrites in a cell subtype-specific manner. However, identification of morphological subtypes of RGCs before they have achieved their mature dendritic pattern is a major challenge in the study of RGC dendritic development. This problem is now being circumvented through the use of molecular markers in genetically engineered mouse lines to identify RGC subsets early during development. Another unanswered fundamental question in the study of activity-dependent refinement of RGC dendrites is how changes in synaptic activity lead to the changes in dendritic morphology. Recent studies have started to shed light on the molecular basis of activity-dependent dendritic refinement of RGCs by showing that some molecular cascades control the cytoskeleton reorganization of RGCs.

Rod‐cone crossover connectome of mammalian bipolar cells

“…As rods can operate at photopic levels in the absence of cone‐driven suppression (Aguilar and Stiles, ), rod‐cone crossover suppression networks may be critical in stabilizing perception and especially susceptible to altered developmental experience. These findings suggest that critical period events that have powerful effects on central mechanisms may also have exceptionally potent influences on the maturation of retinal synaptic network, presaged by the findings of Ikeda and Wright () and strongly demonstrated by Tian and Copenhagan (Tian and Copenhagen, ; Tian, ).…”

Essential Roles of Tbr1 in the Formation and Maintenance of the Orientation-Selective J-RGCs and a Group of OFF-Sustained RGCs in Mouse

“…Shortly after birth, RGC axons further navigate in and around their target nuclei for terminal refinement and establish an orderly representation of the visual field (Herrera et al, 2017, Erskine and Herrera, 2014). While RGC dendritic ramification appears before the RGC axons innervate their terminal targets (Holt, 1989), RGC subtypes with distinctive dendritic morphologies and proper synaptic connections are fully established in postnatal stages, which are regulated in part by molecular cues and/or visual experience (Tian, 2011). How retina-to-brain connections during development and how axonal terminal refinement in target sites contribute to terminal RGC type specification is unknown.…”

Retinal ganglion cell dendrite pathology and synapse loss

“…To achieve functional specificity, RGC dendrites must be confined to specific strata within the inner plexiform layer in order to synapse with a small group of amacrine and bipolar neurons (Wassle, 2004). The mechanisms by which RGC dendrites become confined to specific lamina are still an open question, but both extrinsic molecular cues and activity-dependent refinement have been proposed (Atkinson-Leadbeater and McFarlane, 2011;Tian, 2011).…”