Effects of neuronal variability on phase synchronization of neural networks

TL;DR

This study investigates how neuronal variability influences phase synchronization in neural networks, revealing that higher variability leads to increased promiscuity and affects neural communication effectiveness.

Contribution

It demonstrates the link between neuronal variability and phase synchronization, introducing the concept of promiscuity and its relation to variability in neural networks.

Findings

Higher variability correlates with increased phase synchronization.

Spatial variability is positively linked to promiscuity in phase relations.

Variability influences both the degree and manner of neural phase synchronization.

Abstract

An important idea in neural information processing is the communication-through-coherence hypothesis, according to which communication between two brain regions is effective only if they are phase-locked. Also of importance is neuronal variability, a phenomenon in which a single neuron's inter-firing times may be highly variable. In this work, we aim to connect these two ideas by studying the effects of that variability on the capability of neurons to reach phase synchronization. We simulate a network of modified-Hodgkin-Huxley-bursting neurons possessing a small-world topology. First, variability is shown to be correlated with the average degree of phase synchronization of the network. Next, restricting to spatial variability - which measures the deviation of firing times between all neurons in the network - we show that it is positively correlated to a behavior we call promiscuity, which is the tendency of neurons to to have their relative phases change with time. This relation is observed in all cases we tested, regardless of the degree of synchronization or the strength of the inter-neuronal coupling: high variability implies high promiscuity (low duration of phase-locking), even if the network as a whole is synchronized and the coupling is strong. We argue that spatial variability actually generates promiscuity. Therefore, we conclude that variability has a strong influence on both the degree and the manner in which neurons phase synchronize, which is another reason for its relevance in neural communication.