Pairing cellular and synaptic dynamics into building blocks of rhythmic neural circuits. A tutorial.

Area of Science:

• Neuroscience
• Computational Biology
• Systems Biology

Background:

• Swim central pattern generators (CPGs) in sea slugs like *Melibe leonina* and *Dendronotus iris* utilize complex neural circuitry.
• Two specific subnetworks within these CPGs are known to generate rhythmic bursting patterns.

Purpose of the Study:

• To investigate if these two subnetworks are independently capable of stable network bursting.
• To explore the role of redundant bursting mechanisms in rhythm generation and regulation within swim CPGs.
• To analyze the cellular and synaptic properties crucial for network assembly and function.

Main Methods:

• Slow-fast decomposition analysis of cellular dynamics in isolated and coupled neurons.
• Introduction and examination of a novel model for slow synapses with high filtering efficiency and temporal delay.
• Analysis of two pairwise rhythm-generating networks.

Main Results:

• Demonstrated independent stable network bursting capabilities of the two subnetworks.
• Identified two distinct modes of oscillation in bicellular rhythm-generating networks with network hysteresis: half-center oscillator and excitatory-inhibitory pair.
• Highlighted significant cellular dynamic bifurcations and the properties of novel slow synapses.

Conclusions:

• The two subnetworks are independently capable of producing stable emergent network bursting.
• Bicellular networks exhibiting hysteresis can function as fundamental building blocks in modular neural circuit organization.
• These findings provide insights into the robust network hysteresis observed in larger neural circuits.