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Acetylcholine Boosts Dendritic NMDA Spikes in a CA3 Pyramidal Neuron Model
Rachel Humphries1, Jack R Mellor2, Cian O'Donnell3
1Center for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol BS8 1TD, UK; Computational Neuroscience Unit, School of Computer Science, Electrical and Electronic Engineering, and Engineering Mathematics, University of Bristol, Bristol BS8 1UB, UK.
Neuroscience
|November 15, 2021
Summary
Acetylcholine enhances memory formation by facilitating NMDA spikes in hippocampal CA3 neurons. This neurotransmitter boosts dendritic excitability, strengthening neural connections essential for memory ensembles.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Synaptic Plasticity
Background:
- Acetylcholine is implicated in memory formation.
- Synaptic plasticity in the hippocampal CA3 network is crucial for memory ensembles.
- NMDA receptor (NMDAR) activation, specifically NMDA spikes, can trigger synaptic plasticity.
Purpose of the Study:
- To investigate NMDAR-mediated nonlinear synaptic integration in CA3 neuron dendrites.
- To model the effect of cholinergic inhibition of potassium conductances on dendritic excitability and NMDA spike generation.
- To understand how acetylcholine influences the formation of memory ensembles.
Main Methods:
- Utilized a reconstructed CA3 neuron computational model.
- Simulated cholinergic effects by blocking various potassium channels (M-type, A-type, Ca2+-activated, inwardly-rectifying).
- Analyzed NMDAR-mediated nonlinear synaptic integration in stratum radiatum (SR) and stratum lacunosum moleculare (SLM) dendrites.
Main Results:
- Distal SLM dendrites exhibited a lower threshold for NMDA spike generation compared to SR dendrites due to higher input resistance.
- Simulated acetylcholine significantly increased dendritic excitability and reduced the synaptic input required for NMDA spike generation, particularly in SR dendrites.
- The effect of acetylcholine on NMDA spike generation was heterogeneous across different dendritic branches.
Conclusions:
- Acetylcholine facilitates dendritic integration and NMDA spike generation in specific CA3 neuron dendrites.
- This facilitation by acetylcholine can strengthen connections between CA3 neurons, supporting the formation of memory ensembles.
- The findings provide a mechanistic insight into acetylcholine's role in memory consolidation.
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