Summary
This dissertation study examines how retinal activity shapes the development of visual projections and how photoreceptor degeneration affects downstream visual function, including melanopsin-driven pupillary light responses. Findings suggest that once visual projections are established, they are relatively stable even with significant retinal remodeling, and that reduced melanopsin signaling—rather than downstream deficits—accounts for diminished pupillary light responses in degenerated retinas.
Key Findings
- Abnormal retinal activity in Gβ5-/- mice correlated with impaired eye-specific segregation in the lateral geniculate nucleus at multiple timepoints (P7, P12, P14, P28), with a temporary recovery at P10 matching a normal transition in retinal drive.
- The critical period for eye-specific segregation appears to close shortly after P14, based on activity-segregation profiles in nobxGβ5-/- and Gβ5-/- mice.
- In mice with photoreceptor degeneration (ΔCT and TG9N models), pupillary light responses were diminished, attributed specifically to reduced melanopsin signal in the retina rather than anomalies in downstream visual pathways.
- Gross anatomical and physiological retinofugal connectivity was retained in photoreceptor degeneration mice despite attenuated visual activity and retinal remodeling, suggesting structural resilience of established projections.
Categories
The Science of Light: Examines melanopsin signaling and its role in pupillary light responses in the context of photoreceptor degeneration and retinal remodeling.
Eye Health & Vision: Investigates retinal remodeling after photoreceptor degeneration and its effects on visual pathway connectivity and functional responses.
Author(s)
D Morhardt
Publication Year
2010
Related Publications
The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
- Color appearance models
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice
Eye Health & Vision
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Genetic reactivation of cone photoreceptors restores visual responses in retinitis pigmentosa
- Melanopsin and rod–cone photoreceptors play different roles in mediating pupillary light responses during exposure to continuous light in humans
- Characteristic patterns of dendritic remodeling in early-stage glaucoma: evidence from genetically identified retinal ganglion cell types
- Intrinsically photosensitive melanopsin retinal ganglion cell contributions to the pupillary light reflex and circadian rhythm