Stabilization of memory States by stochastic facilitating synapses.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Neural Circuits

Background:

• Bistability in neural circuits arises from excitatory recurrent feedback.
• Activity state stability depends on firing-rate curves, feedback strength, spike timing, and neuron count.

Purpose of the Study:

• To investigate how synaptic facilitation and depression affect the stability of neural activity states.
• To analyze the impact of dynamic synapses on neural circuit bistability and memory.

Main Methods:

• Analytic methods with approximate formulae were used.
• Simulations of Poisson processes and noisy spiking model neurons were conducted.
• Distributions of synaptic vesicle inter-release intervals were calculated for dynamic synapses.

Main Results:

• Synaptic facilitation greatly enhances neural circuit stability.
• Synaptic depression reduces stability.
• Facilitating synapses increase the curvature of neural input-output functions, widening bistability regions and enhancing memory state lifetimes.
• The coefficient of variation of release intervals differs from interspike intervals for dynamic synapses.

Conclusions:

• Synaptic dynamics, particularly facilitation, play a crucial role in stabilizing neural activity and supporting memory.
• Understanding synaptic plasticity is key to comprehending neural computation and information storage.
• Dynamic synapses alter synaptic efficacy based on input rates, influencing circuit behavior.