Chimera-like States in Modular Neural Networks

Inspired by the ancient Greek mythological creature Chimera, which had a lion's head, a goat's body and a serpent's tail, Abrams and Strogatz coined the term "chimera states" for the counter-intuitive self-organized phenomenon in which synchronous and desynchronous oscillatory behavior coexist in the same system. It is believed that these states may be related to unihemispheric sleep, observed in birds and dolphins, as they are found to sleep with one eye open, meaning that half of their brain is synchronized whilst the other half is desynchronized. Chimera states were previously analyzed in complex networks. However, they have not been extensively studied in modular networks, where interactions within and across modules are attributed to different types of links that play their own roles in the self-organized dynamics.

Here, we consider the neural network of the C.elegans soil worm, equipped with electrical and chemical neural synapses for communication. Using a community detection method, we split its neural network into six interconnected communities. We also assume that neurons obey chaotic bursting dynamics and are connected with electrical synapses within their communities and with chemical across them.

The co-action of these synapses has been studied by means of numerical simulations and was revealed that they are able to drive the dynamics to the emergence of chimera-like states, evidenced by the coexistence of strongly synchronized and desynchronized communities of neurons. A topological analysis of the network's structure has revealed that the most populated communities drive this peculiar phenomenon, being the most influential among all. Our findings are further supported by similar results we obtained for other modular networks that share similar topological characteristics with the C.elegans neural.

Nature - Scientific Reports