Microcircuit synchronization and heavy tailed synaptic weight distribution in preB\"otzinger Complex contribute to generation of breathing rhythm

TL;DR

This study models the preB"otzinger Complex microcircuit to understand how synchronization and heavy-tailed synaptic weight distributions contribute to breathing rhythm generation, revealing mechanisms of variability and robustness.

Contribution

It demonstrates that directed Erd ext{"o}s-Rényi graphs and lognormal synaptic weight distributions are essential for replicating experimental breathing rhythm dynamics in minimal models.

Findings

Directed Erd ext{"o}s-Rényi graphs best match experimental data.

Heavy-tailed synaptic weights enhance input convergence efficacy.

Synchronization mechanisms regulate rhythm variability and robustness.

Abstract

The preB\"otzinger Complex, the mammalian inspiratory rhythm generator, encodes inspiratory time as motor pattern. Spike synchronization throughout this sparsely connected network generates inspiratory bursts albeit with variable latencies after preinspiratory activity onset in each breathing cycle. Using preB\"otC rhythmogenic microcircuit minimal models, we examined the variability in probability and latency to burst, mimicking experiments. Among various physiologically plausible graphs of 1000 point neurons with experimentally determined neuronal and synaptic parameters, directed Erd\H{o}s-R\'enyi graphs best captured the experimentally observed dynamics. Mechanistically, preB\"otC (de)synchronization and oscillatory dynamics are regulated by the efferent connectivity of spiking neurons that gates the amplification of modest preinspiratory activity through input convergence. Furthermore, to replicate experiments, a lognormal distribution of synaptic weights was necessary to augment the efficacy of convergent coincident inputs. These mechanisms enable exceptionally robust yet flexible preB\"otC attractor dynamics that, we postulate, represent universal temporal-processing and decision-making computational motifs throughout the brain.