The prevailing theory of nerve signal propagation holds that signals are transmitted via depolarization of membrane potential. This involves voltage gated ion channels and cross-membrane ion movement (top left inset).
A more recent theory of nerve signaling (the Heimburg model) describes the signal instead as a physical wave through the axon membrane (bottom right inset).
This visual was created with Maxon Cinema4D, Adobe Photoshop, and Adobe Illustrator.
Fox, Douglas. 2018. “The Brain, Reimagined.” Scientific American 318(4): 65.