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Behaviorally relevant, higher order representations of an animal’s environment are built from the convergence of visual features encoded in the early stages of visual processing. Although developmental mechanisms that generate feature encoding channels in early visual circuits have been uncovered, relatively little is known about the mechanisms that direct feature convergence to enable appropriate integration into downstream circuits. Here we explore the development of a collision detection sensorimotor circuit in Drosophila melanogaster, the convergence of visual projection neurons (VPNs) onto the dendrites of a large descending neuron, the giant fiber (GF). We find VPNs encoding different visual features establish their respective territories on GF dendrites through sequential axon arrival during development. Physical occupancy, but not developmental activity, is important to maintain territories. Ablation of one VPN results in the expansion of remaining VPN territories and functional compensation that enables the GF to retain responses to ethologically relevant visual stimuli. GF developmental activity, observed using a pupal electrophysiology preparation, appears after VPN territories are established, and likely contributes to later stages of synapse assembly and refinement. Our data highlight temporal mechanisms for visual feature convergence and promote the GF circuit and the Drosophila optic glomeruli, where VPN to GF connectivity resides, as a powerful developmental model for investigating complex wiring programs and developmental plasticity.
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This content will become publicly available on July 1, 2026
Distinct Developmental Programs Displayed by the Xenopus Tadpole Accessory Optic System and Retinotectal Projection
ABSTRACT The retinotectal projection, the direct synapse between retinal ganglion cells (RGCs) of the eye and tectal neurons of the optic tectum, is a major component of the amphibian visual system. A model of circuit formation, this projection has been studied in detail. There are, however, other retinorecipient targets that also comprise the amphibian visual system such as the pretectum and ventral midbrain tegmentum. Understanding how these other components of the visual system form and function will lead to a more comprehensive understanding of how the visual system, as a whole, assembles and functions. Toward this aim, here we describe the functional development of theXenopustadpole accessory optic system (AOS), a direct synaptic connection between RGC axons and the basal optic nucleus of the midbrain tegmentum. The AOS is highly conserved across vertebrates. It functions as the sensory side of the optokinetic and optomotor reflexes, compensatory eye and body movements, respectively, that stabilize the visual scene as the organism moves through it. Using an isolated brain preparation and whole‐cell electrophysiological approaches, we compared the development of the AOS and retinotectal projection. We found that these two retinofugal projections display distinct developmental programs, which appear to mirror their different functions. Retinotectal synapses moved through a dynamic phase of previously described NMDA receptor‐dependent refinement, a process that is known to sharpen the retinotopic map and thereby visual acuity. In contrast, the AOS synapse appeared more stable and activity independent across development, indicative of a hardwired circuit, built to support reflexive optic behaviors.
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- Award ID(s):
- 2212591
- PAR ID:
- 10653473
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Developmental Neurobiology
- Volume:
- 85
- Issue:
- 3
- ISSN:
- 1932-8451
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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