Neuron Firing Simulator
Stimulate a neuron and watch the action potential travel along the axon.
Press Stimulate, or drag the orange handle to set how strong the stimulus is. Only a big enough stimulus makes the neuron fire.
About the Neuron Firing Simulator
Free neuron simulator. Deliver a stimulus of any strength, watch the membrane voltage graph, the threshold, the refractory period and the nerve impulse travelling down the axon. Built for biology, the neuron firing simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Stimulate a neuron and watch the action potential travel along the axon. Use it to explore biology ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Neuron Firing Simulator
- Use the controls to change Stimulus strength. The simulation reacts instantly.
- Pick an option such as Single pulse, Constant current to switch modes or load an example.
- Press "Stimulate", "Reset" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Give a weak stimulus and then a strong one.
- Fire two stimuli quickly and see the refractory period.
- Hold a constant current and see repeated firing.
- Watch the sodium and potassium channels.
Key ideas you can learn
- A neuron only fires if the stimulus reaches the threshold (all-or-nothing).
- Sodium channels open to depolarise the cell, then potassium channels open to repolarise it.
- After a spike there is a refractory period when it cannot fire again.
Where this is used in the real world
Nerve signals carry every sensation and movement in your body. Doctors use the same principles in ECG and EEG tests and to understand anaesthetics and epilepsy drugs.
Who is this simulation for?
Biology students and teachers who want to explore living systems, populations and genetics interactively and safely.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
What is an action potential?
A brief, rapid rise and fall in the voltage across a neuron's membrane that travels along the axon as a nerve signal.
Why is it called all-or-nothing?
Once the threshold is reached, the spike has the same size regardless of how strong the stimulus was.
Is the Neuron Firing Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Neuron Firing Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.