Emergent memory in cell-like active systems

TL;DR

This paper introduces a theoretical framework for active systems with internal state dynamics and environmental sensing, revealing how memory effects lead to complex behaviors in cell-like active agents.

Contribution

It extends existing models by incorporating internal state dynamics and environmental feedback, demonstrating emergent memory effects in active particle systems.

Findings

Memory-induced responses in active agents

Enhanced jamming transitions due to memory effects

Suppression of motility-induced phase separation

Abstract

Active systems across scales, ranging from molecular machines to human crowds, are usually modeled as assemblies of self-propelled particles driven by internally generated forces. However, these models often assume memoryless dynamics and no coupling of internal active forces to the environment. Here, guided by the example of living cells, which have recently been shown to display multi-timescale memory effects, we introduce a general theoretical framework that goes beyond this paradigm by incorporating internal state dynamics and environmental sensing into active particle models. We show that when the self-propulsion of an agent depends on internal variables with their own complex dynamics - modulated by local environmental cues - environmental memory spontaneously emerges and gives rise to new classes of behaviours. These include memory-induced responses, adaptable localization in complex landscapes, suppression of motility-induced phase separation, and enhanced jamming transitions. Our results demonstrate how minimal information processing capabilities, intrinsic to non-equilibrium agents with internal states like living cells, can profoundly influence both individual and collective behaviours. This framework bridges cell-scale activity and large-scale intelligent motion in cell assemblies, and opens the way to the quantitative analysis and design of systems ranging from synthetic colloids to biological collectives and robotic swarms.