An action potential, interactive

One mossy fiber and the CA3 pyramidal cell it contacts. Drag to orbit, scroll to zoom, scrub to move the signal.

0µm of cable
at rest
This viewer needs WebGL, which your browser has not made available. The rendered animations on the main page show the same event.
The pulse is not a sweep across the screen. Every vertex of these meshes carries its own distance measured along the cell's own skeleton, so the wavefront follows the real branching and splits wherever the cable splits. The signal travels the fiber to the boutons, then from the thorn through the cell to the soma, 130.5 µm of cable away, and out along the descending arbor. The 31% of dendrite it never enters stays dark, because that is where it does not go.

Simplified for the browser: 110,000 faces against 4.5 million in the rendered version, so the thorny excrescences are smoothed away here.