Critical behavior in the Artificial Axon

TL;DR

The paper investigates the critical firing threshold of the Artificial Axon, a synthetic neuron-like system, demonstrating that its behavior near threshold mirrors real neurons and validating a minimal theoretical model with experimental data.

Contribution

It introduces a minimal Morris-Lecar type model for the Artificial Axon and confirms its predictions through experiments, highlighting universal properties of neuronal firing.

Findings

Firing delay scales with the threshold distance as -1/2 exponent.

The minimal model accurately predicts experimental results.

Firing threshold depends on the number of ion channels.

Abstract

The Artificial Axon is a unique synthetic system, based on biomolecular components, which supports action potentials. Here we examine, experimentally and theoretically, the properties of the threshold for firing in this system. As in real neurons, this threshold corresponds to the critical point of a saddle-node bifurcation. We measure the delay time for firing as a function of the distance to threshold, recovering the expected scaling exponent of $- 1/2$. We introduce a minimal model of the Morris-Lecar type, validate it on the experiments, and use it to extend analytical results obtained in the limit of "fast" ion channel dynamics. In particular, we discuss the dependence of the firing threshold on the number of channels. The Artificial Axon is a simplified system, an Ur-neuron, relying on only one ion channel species for functioning. Nonetheless, universal properties such as the action potential behavior near threshold are the same as in real neurons. Thus we may think of the Artificial Axon as a cell-free breadboard for electrophysiology research.