Spontaneous generation of persistent activity in diffusively coupled cellular assemblies

TL;DR

This paper explores how spontaneous, persistent electrical activity can emerge in assemblies of diffusively coupled cells, including passive and active types, revealing complex dynamics and simplified collective behaviors.

Contribution

It demonstrates that non-oscillatory cells can generate sustained activity through diffusive coupling, and introduces a reduced model capturing these phenomena.

Findings

Assemblies exhibit chaos and synchronized oscillations.

Spatio-temporal patterns depend on coupling and cell properties.

Reduced models replicate complex emergent behaviors.

Abstract

The spontaneous generation of electrical activity underpins a number of essential physiological processes, and is observed even in tissues where specialized pacemaker cells have not been identified. The emergence of periodic oscillations in diffusively coupled assemblies of excitable and electrically passive cells (which are individually incapable of sustaining autonomous activity) has been suggested as a possible mechanism underlying such phenomena. In this paper we investigate the dynamics of such assemblies in more detail by considering simple motifs of coupled electrically active and passive cells. The resulting behavior encompasses a wide range of dynamical phenomena, including chaos. However, embedding such assemblies in a lattice yields spatio-temporal patterns that either correspond to a quiescent state or partial/globally synchronized oscillations. The resulting reduction in dynamical complexity suggests an emergent simplicity in the collective dynamics of such large, spatially extended systems. Furthermore, we show that such patterns can be reproduced by a reduced model comprising only excitatory and oscillatory elements. Our results suggest a generalization of the mechanism by which periodic activity can emerge in a heterogeneous system comprising non-oscillatory elements by coupling them diffusively, provided their steady states in isolation are sufficiently dissimilar.