Neuron Explorer¶
Run the Neuron Explorer MicroSim fullscreen
About This MicroSim¶
Neuron Explorer shows a labeled neuron (dendrites, cell body, axon hillock, axon, myelin sheath, nodes of Ranvier, and axon terminals) next to two kinds of glial cells: an oligodendrocyte that wraps myelin around the axon and an astrocyte whose "end-foot" touches a blood vessel. Hover over, click, or choose any part to read its job in the info panel.
The Send signal button fires a signal at the start of the axon. With healthy myelin, the signal races along and is renewed at each node of Ranvier. Check Remove myelin (MS) to strip myelin from 1 to 4 segments, as happens in multiple sclerosis. In the bare stretch, the signal leaks charge, slows to a crawl, and fades. One or two damaged segments make it arrive late. Three or four damaged segments make it fade out before it reaches a healthy node, so the message is blocked.
The signal model is simplified and illustrative. The speeds and fading rate are chosen to show the pattern, not measured from a real nerve. Real conduction speeds are given in the chapter.
How to Use¶
- Hover over (or click) each labeled part. Read its job in the info panel at the bottom. You can also pick a part from the Explore a part menu.
- Press Send signal with healthy myelin. Watch the signal flash at each node and reach the axon terminals.
- Check Remove myelin (MS) and leave Damaged segments at 2. Send the signal again. Compare its speed and strength with step 2.
- Move the slider to 3 or 4 damaged segments and send another signal. What happens this time?
- Use Pause / Resume to freeze the signal and read the strength value in the status line.
Learning Objective¶
Bloom level: Understand (explain). Students will be able to explain the job of each part of a neuron and its nearby glial cells, and explain why losing myelin (as in multiple sclerosis) makes a signal slower and can stop it completely.
Iframe Embed Code¶
<iframe src="https://aaryavvatts-lab.github.io/neuroscience-textbook/sims/ch01-neuron-explorer/main.html" height="637px" width="100%" scrolling="no"></iframe>
Lesson Plan¶
Grade level: 9 to 12 (biology, anatomy and physiology, or a neuroscience club)
Duration: 15 to 20 minutes
Prerequisites: Basic cell structure (nucleus, cell membrane, proteins). Students should have read Sections 1.4 to 1.7 of Chapter 1.
Activity:
- Label race (5 min). In pairs, one student names a part's job out loud ("collects incoming messages") and the partner finds the part in the sim and checks the info panel.
- Predict, then test (5 min). Before removing any myelin, students write a prediction: "If myelin is removed from two segments, the signal will..." Then they test it and record what happened.
- Find the breaking point (5 min). Students raise the number of damaged segments one at a time and record the first setting where the signal is blocked.
- Connect to medicine (5 min). Students explain in two sentences how this links to the blurry vision and tingling in the chapter's multiple sclerosis case.
Assessment questions:
- Which glial cell in the sim makes myelin in the brain and spinal cord? What makes myelin in the rest of the body?
- Why does the signal get renewed at nodes of Ranvier but fade in a bare stretch of axon?
- In the sim, removing myelin from two segments slows the signal, but removing it from three segments blocks it. Explain this difference in your own words.
- MS symptoms can come and go. Using the sim, explain how a small amount of damage might cause a slowed signal while a larger patch causes a lost signal.