Chimera states in a multilayer network of coupled and uncoupled neurons

TL;DR

This paper investigates how chimera states emerge in a multilayer neuronal network with coupled and uncoupled layers, highlighting the roles of synaptic types, network structure, and transmission delays in pattern formation.

Contribution

It introduces a multilayer neuronal network model with mixed synaptic connections and demonstrates the conditions under which chimera states arise, including the effects of delays and synaptic types.

Findings

Chimera states occur regardless of electrical synapse range within the coupled layer.

Between-layer chimera states are observed with all-to-all and nearest-neighbor coupling.

Transmission delay influences the expansion of chimera regions and state transitions.

Abstract

We study the emergence of chimera states in a multilayer neuronal network, where one layer is composed of coupled and the other layer of uncoupled neurons. Through the multilayer structure, the layer with coupled neurons acts as the medium by means of which neurons in the uncoupled layer share information in spite of the absent physical connections among them. Neurons in the coupled layer are connected with electrical synapses, while across the two layers neurons are connected through chemical synapses. In both layers the dynamics of each neuron is described by the Hindmarsh-Rose square wave bursting dynamics. We show that the presence of two different types of connecting synapses within and between the two layers, together with the multilayer network structure, plays a key role in the emergence of between-layer synchronous chimera states and patterns of synchronous clusters. In particular, we find that these chimera states can emerge in the coupled layer regardless of the range of electrical synapses. Even in all-to-all and nearest-neighbor coupling within the coupled layer, we observe qualitatively identical between-layer chimera states. Moreover, we show that the role of information transmission delay between the two layers must not be neglected, and we obtain precise parameter bounds at which chimera states can be observed. The expansion of the chimera region and annihilation of cluster and fully coherent states in the parameter plane for increasing values of inter-layer chemical synaptic time delay are illustrated using effective range measurement. These results are discussed in the light of neuronal evolution, where the coexistence of coherent and incoherent dynamics during the developmental stage is particularly likely.