Summary
This study used advanced electron microscopy to map how melanopsin-expressing retinal ganglion cells (mRGCs) connect within the suprachiasmatic nucleus (SCN), the brain's master circadian clock. The findings challenge current models of light signal integration in the SCN, with implications for understanding how lighting conditions entrain circadian rhythms at a neural circuit level.
Key Findings
- The SCN shell receives denser mRGC synaptic inputs compared to the core, contradicting the prevailing view that photic information from the retina is primarily integrated by the core region.
- Using APEX2 (a Cre-dependent EM reporter) and serial blockface scanning electron microscopy (SBEM), the study generated the first 3D connectomic maps of mRGC axonal organization across SCN sub-regions.
- Core and shell sub-regions of the SCN differ in their neuronal subtypes and in the patterning of mRGC inputs, suggesting differential roles in processing light information.
Categories
The Science of Light: Investigates the synaptic connectivity of melanopsin-expressing retinal ganglion cell (mRGC) axons within the SCN, directly relevant to understanding photic entrainment of the circadian clock.
Author(s)
H Calligaro, A Shoghi, X Chen, KY Kim, YH Liu, B Khov
Publication Year
2022
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