A small neural network with three inputs, two hidden layers of five neurons and two outputs is drawn in 3D. Students move the input sliders and watch neuron colors, connection weights and the two outputs change.
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Neuron Signal
About this simulation
This model shows a nerve impulse moving along an axon, colored by membrane voltage: blue at rest, cyan at threshold and yellow at the peak. Students press Stimulate or leave Auto-fire on, switch the myelin sheath on and off, and change the axon diameter from 1 to 20 micrometers. Readouts show the voltage at a probe, the phase of the action potential, the conduction speed and when the signal reaches the terminal. It helps explain resting potential, depolarization and repolarization, and why myelinated fibers conduct impulses much faster.
What students can explore
- Press Stimulate and watch the Voltage at probe readout rise from about -70 mV to a peak.
- Switch Myelin sheath off and compare the Conduction speed and Reaches terminal values.
- Increase Axon diameter and note how speed changes with and without myelin.
- Turn Auto-fire off to send one impulse at a time and read the Phase at each moment.
- Match the colors blue, cyan and yellow to rest, threshold and peak.
Learning objectives
- 1Describe the resting potential, threshold and peak of an action potential.
- 2Explain how sodium and potassium channels cause depolarization and repolarization.
- 3Explain how myelin and nodes of Ranvier speed up conduction.
- 4Predict how axon diameter and myelination change signal speed.
Questions teachers ask
Is the neuron signal simulation free?
Yes. It is free and runs in any modern browser, including interactive whiteboards and tablets. There is no sign-up and nothing to install.
What is an action potential?
It is a brief reversal of the voltage across a neuron's membrane, from about -70 mV to about +40 mV and back. Sodium channels open first, then potassium channels restore the resting voltage.
Why does myelin make signals faster?
Myelin insulates the axon, so the impulse regenerates only at the gaps called nodes of Ranvier and effectively jumps between them. This saltatory conduction can reach 60 to 120 m/s in thick fibers.
Is the timing in the model real?
No. The animation is slowed about 40 times, and node spacing is exaggerated. The speeds in the readout come from standard approximations for myelinated and unmyelinated axons.
Embed this simulation
Drop it into your LMS, blog, or class site — free.
<iframe src="https://kiwibee.io/en/simulations/neuron-signal-3d-simulation/embed" title="Neuron Signal | KiwiBee" loading="lazy" allowfullscreen style="width:100%;height:min(70vh,620px);min-height:420px;border:0;border-radius:16px"></iframe>Continue exploring
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