Time-coded neurotransmitter release at excitatory and inhibitory synapses

Area of Science:

• Neuroscience
• Molecular Biology
• Computational Biology

Background:

• Neuronal communication relies on regulated neurotransmitter release from vesicles at chemical synapses.
• Mechanisms for asynchronous and spontaneous neurotransmitter release, distinct from stimulus-evoked release, are not fully understood.
• Short-term synaptic plasticity (STSP) involves dynamic changes in synaptic strength following neuronal activity.

Purpose of the Study:

• To develop a comprehensive model of the vesicle exocytotic cycle that explains all modes of neurotransmitter release.
• To elucidate the molecular mechanisms underlying asynchronous and spontaneous neurotransmitter release.
• To provide a framework for understanding short-term synaptic plasticity (STSP).

Main Methods:

• Development of a mathematical model for the exocytotic cycle of synaptic vesicles.
• Incorporation of protein dynamics, including SNARE complex assembly and function.
• Simulation of vesicle release under various conditions, including spontaneous and asynchronous events.

Main Results:

• The model successfully accounts for stimulus-evoked, asynchronous, and spontaneous modes of vesicle release.
• A key prediction for asynchronous release involves delayed inertial protein unbinding during SNARE complex assembly post-priming.
• The model also explains various forms of short-term synaptic plasticity (STSP).

Conclusions:

• The proposed model offers a unified explanation for diverse neurotransmitter release patterns at chemical synapses.
• The model's predictions provide testable hypotheses for experimental validation of molecular mechanisms.
• The model's simplicity facilitates large-scale simulations of neural circuits, advancing our understanding of brain function.