Rapid multi-directed cholinergic transmission in the central nervous system.
Santhosh Sethuramanujam1, Akihiro Matsumoto2, Geoff deRosenroll1
1Department of Biology, University of Victoria, Victoria, BC, Canada.
Nature Communications
|March 3, 2021
Summary
This study reveals how acetylcholine (ACh) transmission in the retina uses a unique tripartite structure for rapid, multi-neuron signaling. This mechanism enables direction-selective visual processing in the brain.
Area of Science:
- Neuroscience
- Cell Biology
- Visual System Research
Background:
- Cholinergic transmission in the central nervous system (CNS) can occur via rapid synaptic or slower non-synaptic mechanisms.
- The precise mode of cholinergic signaling in the retina, particularly involving starburst amacrine cells, remains incompletely understood.
Purpose of the Study:
- To investigate the ultrastructural basis and functional properties of cholinergic signaling between starburst amacrine cells and ganglion cells.
- To elucidate the operational framework of acetylcholine (ACh) release and receptor activation in retinal circuits.
Main Methods:
- Utilized serial electron microscopy to analyze the ultrastructure of cholinergic connections.
- Employed electrophysiology and two-photon imaging of ACh to assess functional properties.
- Correlated structural findings with functional data to understand transmission dynamics.
Main Results:
- Identified a 'tripartite' structure facilitating 'multi-directed' ACh transmission.
- Demonstrated rapid co-activation of receptors in multiple neurons within ~1 µm of release sites (~1 ms).
- Showed that cholinergic signals are direction-selective locally, not globally, aiding information transfer.
Conclusions:
- Proposed a novel operational framework for cholinergic signaling, integrating aspects of both synaptic and non-synaptic transmission.
- Highlighted the role of this unique signaling mode in local direction selectivity within the retina.
- Emphasized the importance of ultrastructural organization in shaping neural signal transmission.
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