Electromagnetic Propagation Models in Nerve Fibers

They explain how electromagnetic propagation is the most parsimonious explanation for the action potential propagation along myelinated axons of neurons, because of the velocities of propagation are more faster on these axons (semi-instantaneous), but also they say that in unmyelinated axons, that is in the rest of neurons (more simple, non-vertebrate specific), also electromagnetic propagation may occur (but with the difference that nerve signals need to be regenerated very frequently, so conduction speed is slower).

This is the most probable because a recent finding found that transmembrane ionic flow is also excessively slow to take part on a parallel propagation of the potential [1].

[1] Tarun, Orly B., et al. "Spatiotemporal imaging of water in operating voltage-gated ion channels reveals the slow motion of interfacial ions." Nano Letters (2019).