Summary
This study reveals that suprachiasmatic nucleus neurons are physically connected via large soma-to-soma plate-like contacts (ephapses) covering ~21% of apposing cell surfaces, suggesting a non-synaptic electrical coupling mechanism for circadian synchronization. This finding may explain how the SCN maintains coordinated circadian rhythms even when conventional chemical or gap-junction synaptic transmission is blocked, deepening the fundamental understanding of the clock system that lighting interventions aim to influence.
Key Findings
- Ephaptic (soma-to-soma plate-like) contacts between SCN core neurons covered on average ~21% of the surface area of apposing neuronal somata.
- 805 coronal ultrathin sections were imaged and reconstructed into a 3D volumetric stack, with selected SCN core neurons reconstructed in silico.
- These contacts may serve as the electrophysiological substrate for SCN neuron synchronization, potentially explaining maintained synchrony when both chemical synaptic transmission and gap junctions are blocked.
Categories
The Science of Light: Provides ultrastructural evidence for a novel synchronization mechanism in the SCN, the master circadian pacemaker, with implications for understanding how circadian rhythms are maintained.
Author(s)
MÉ Czeisler, Y Shan, R Schalek, DR Berger
Publication Year
2022
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