RT Journal Article SR Electronic T1 An electrophysiological and behavioral model of Paramecium, the “swimming neuron” JF bioRxiv FD Cold Spring Harbor Laboratory SP 2022.02.15.480485 DO 10.1101/2022.02.15.480485 A1 Irene Elices A1 Anirudh Kulkarni A1 Nicolas Escoubet A1 Léa-Laetitia Pontani A1 Alexis Michel Prevost A1 Romain Brette YR 2022 UL http://biorxiv.org/content/early/2022/02/17/2022.02.15.480485.abstract AB Paramecium is a large unicellular organism that swims in fresh water using cilia. When stimulated by various means (mechanically, chemically, optically, thermally), it often swims backward then turns and swims forward again in a new direction: this is called the avoiding reaction. This reaction is triggered by a calcium-based action potential. For this reason, several authors have called Paramecium the “swimming neuron”. Here we present an empirically constrained model of its action potential based on electrophysiology experiments on live immobilized paramecia, together with simultaneous measurement of ciliary beating using particle image velocimetry. Using these measurements and additional behavioral measurements of free swimming, we extend the electrophysiological model by coupling calcium concentration to kinematic parameters, turning it into a swimming model. In this way, we obtain a model of autonomously behaving Paramecium. Finally, we demonstrate how the modeled organism interacts with an environment, can follow gradients and display collective behavior. This work provides a modeling basis for investigating the physiological basis of autonomous behavior of Paramecium in ecological environments.Competing Interest StatementThe authors have declared no competing interest.