Synaptic transmission is driven by a complex cycle of vesicle docking, release, and recycling, maintained by distinct vesicle pools. However, the partitioning of vesicle pools and reserve pool recruitment remain poorly understood. We use a novel vesicle modeling technology to model the synaptic vesicle cycle in unprecedented molecular and spatial detail at a hippocampal synapse. Our model demonstrates robust recycling of synaptic vesicles that maintains consistent synaptic release, even during sustained high frequency firing. We also reveal how the cytosolic proteins synapsin-1 and tomosyn-1 cooperate to regulate recruitment of reserve pool vesicles during sustained firing to maintain transmission, as well as the potential of selective vesicle active zone tethering to ensure rapid vesicle replenishment while minimizing reserve pool recruitment. We also monitored vesicle usage in isolated hippocampal neurons using pH-sensitive pHluorin, demonstrating that reserve vesicle recruitment depends on frequency, even at non-physiologically high firing frequencies, as predicted by the model.
Model Type: Molecular Network; Synapse
Region(s) or Organism(s): Hippocampus
Cell Type(s): Hippocampus CA3 pyramidal GLU cell
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Model Concept(s): Detailed Neuronal Models; Reaction-diffusion; Stochastic simulation
Simulation Environment: STEPS
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