3D simulation · Cells and microbes

How a neuron sends a signal, in 3D

Name: How a thought travels
Uploaded: 2026-11-05
Description: An electrical signal racing down a nerve cell, chemical messengers crossing the gap to the next one, and how fast a thought really travels.

An electrical signal racing down a nerve cell, chemical messengers crossing the gap to the next one, and how fast a thought really travels. Not a drawing and not an AI guess: a simulation that runs the real numbers, narrated, with every moment landing on its word.

Make this video →Free to try · 11 languages · about 3 minutes

What the simulation shows

The neuron, labelled: dendrites (listen), cell body (adds up), axon (the output cable).
A signal (action potential) racing down the axon; the voltage flips from −70 to +40 millivolts as sodium rushes in. It keeps firing after.
Close on the axon: the myelin insulation, and the signal leaping from gap to gap.
Zooms into the synapse: the signal releases chemical messengers that cross a tiny gap to the next neuron.
The next neuron lighting up as it fires in turn.
Zooms out: a network of neurons, signals cascading through it.
A callout: about 430 kilometres an hour, a signal in an insulated nerve.
A counter rolls up to 86 billion: neurons in the brain.

The real numbers it runs on

The simulation is built on these facts, so the narration and the picture always agree:

A neuron has dendrites that receive signals, a cell body that adds them up, and an axon that sends its own signal on.
At rest the inside of a neuron is about −70 millivolts. When it fires, sodium rushes in and the voltage flips to about +40 for about a millisecond: an action potential. It's all-or-nothing.
Myelin is fatty insulation around many axons; the signal leaps from gap to gap, reaching about 120 metres a second (about 430 km/h). Without myelin some signals crawl at about 1 metre a second.
At a synapse, the signal releases chemical messengers (neurotransmitters such as dopamine or serotonin) that cross a gap about 20 millionths of a millimetre wide to the next neuron.
The brain has about 86 billion neurons, each connected to up to thousands of others.
A neuron can fire hundreds of times a second.

The script this video was made from

“How a thought travels”: the narration of the video above. Each highlighted moment in the simulation happens on the word that names it.

Every thought you've ever had was a tiny burst of electricity jumping from cell to cell.

The cell

A neuron listens with its branches and answers down one long cable.

The spark

When it fires, the voltage flips in a millisecond and races down the cable, leaping between gaps in its insulation.

The gap

At the end there's a gap. The signal releases chemical messengers that cross it, and the next neuron fires.

The storm

Now multiply that by 86 billion neurons. That's your brain, thinking.

Make your own

Type a question, like “How a thought travels”, or your own angle on it.
ContentRoof picks this simulation, researches the facts and writes a short script, with every moment cued to a word.
A natural voice reads it in your language and the simulation plays in time with it. Change any line and it follows.
Download a vertical video for Shorts, TikTok and Reels, or use it in class.

Make this video →

Questions

Is this a real simulation or an AI-generated video?

A real simulation. How a neuron sends a signal runs on the numbers listed above, so what you see is what actually happens, frame by frame. AI video generators guess what a scene should look like; they often get the science wrong.

Can I change what the narrator says?

Yes. Type your own question or idea and the AI writes a new script for this simulation, or edit any line yourself. Every moment of the simulation lands on the word that names it.

Which languages can it narrate in?

Eleven: English, Urdu, Hindi, Arabic, Spanish, French, Portuguese, German, Italian, Russian and Polish, with captions written properly (Urdu in Nastaliq, Arabic right to left).

Can I use it in class or post it on YouTube?

Yes. The video is yours to use in lessons, on YouTube Shorts, TikTok and Instagram Reels. The free plan makes 2 3D simulations a month; paid plans make more, in 1080p without the small mark.