Energetic demands of information transmission along axons

Communication at the cellular level is constrained by noise in the environment. In the case of neurons, ion channels need to communicate with each other to collectively generate action potentials. Previous work has shown that electrical communication between ion channels must compete with thermal fluctuations, requiring a minimum amount of energy to send one bit of information. This cost depends on the geometric characteristics of the system and is orders of magnitude larger than some information-theoretic bounds, such as the Landauer bound. In this work, we extend this framework to the collective dynamics of ion channels during action potentials, where the system is far from thermal equilibrium. We apply this analysis to the energetics of action potential propagation in axons. Specifically, we derive bounds on the cost of sending information with action potentials and use these to study the optimality of saltatory conduction in myelinated axons. This analysis is a first step towards understanding design principles in axons, allowing us to explain some of the widely observed features of action potential propagation.