The free energy cost of reducing noise while maintaining a high sensitivity

TL;DR

Biological sensory systems driven far from equilibrium can reduce noise and maintain high sensitivity through free energy consumption, breaking the Fluctuation Dissipation Theorem, as demonstrated in a continuum model of E. coli chemotaxis.

Contribution

This work introduces a continuum theory showing how free energy dissipation enables sensory systems to reduce fluctuations while preserving responsiveness, revealing a non-equilibrium phase transition.

Findings

Maximum response at short times is enhanced by free energy dissipation.

Low frequency fluctuations decrease algebraically with free energy dissipation.

Adaptation error decreases exponentially with free energy dissipation.

Abstract

Living systems need to be highly responsive, and also to keep fluctuations low. These goals are incompatible in equilibrium systems due to the Fluctuation Dissipation Theorem (FDT). Here, we show that biological sensory systems, driven far from equilibrium by free energy consumption, can reduce their intrinsic fluctuations while maintaining high responsiveness. By developing a continuum theory of the E. coli chemotaxis pathway, we demonstrate that adaptation can be understood as a non-equilibrium phase transition controlled by free energy dissipation, and it is characterized by a breaking of the FDT. We show that the maximum response at short time is enhanced by free energy dissipation. At the same time, the low frequency fluctuations and the adaptation error decrease with the free energy dissipation algebraically and exponentially, respectively.