Emergence of Sparsely Synchronized Rhythms and Their Responses to External Stimuli in An Inhomogeneous Small-World Complex Neuronal Network

TL;DR

This study investigates how inhomogeneous small-world neuronal networks exhibit sparsely synchronized rhythms and respond to external stimuli, highlighting the role of network architecture and betweenness centrality in synchronization and communication efficiency.

Contribution

It introduces an analysis of inhomogeneous SWNs with inhibitory interneurons, revealing how varying the fraction of long-range interneurons affects synchronization and response to stimuli, contrasting with Watts-Strogatz networks.

Findings

Sparsely synchronized rhythms emerge at a critical long-range fraction (~0.16).

Increasing long-range connections shortens path length and improves communication efficiency.

Stimuli effects depend on betweenness centrality of targeted interneurons.

Abstract

We consider an inhomogeneous small-world network (SWN) composed of inhibitory short-range (SR) and long-range (LR) interneurons. By varying the fraction of LR interneurons $p_{long}$, we investigate the effect of network architecture on emergence of sparsely synchronized rhythms, and make comparison with that in the Watts-Strogatz SWN. Although SR and LR interneurons have the same average in- and out-degrees, their betweenness centralities (characterizing the potentiality in controlling communication between other interneurons) are distinctly different. Hence, in view of the betweenness, SWNs we consider are inhomogeneous, unlike the "canonical" Watts-Strogatz SWN with nearly same betweenness centralities. As $p_{long}$ is increased, the average path length becomes shorter, and the load of communication traffic is less concentrated on LR interneurons, which leads to better efficiency of global communication between interneurons. Eventually, when passing a critical value $p_{long}^{(c)}$ $(\simeq 0.16)$, sparsely synchronized rhythms are found to emerge. We also consider two cases of external time-periodic stimuli applied to sub-groups of LR and SR interneurons, respectively. Dynamical responses (such as synchronization suppression and enhancement) to these two cases of stimuli are studied and discussed in relation to the betweenness centralities of stimulated interneurons, representing the effectiveness for transfer of stimulation effect in the whole network.