Design idea for demonstrating human nerve electrical messages

Hey Greg - 

Is a video out of the question? Also, does she want to convey a constant flow or a bursty flow? When I taught electronics stuff, we used some animation with masked elements. 

You can build masks in a variety of tools. You can fake it in PowerPoint. Using some layers you could represent a color change and some type of overlay that produces the mental image of "electrical". Something like the attached might do the trick. I brought your image into Photoshop and erased the top line.  I painted in another line, added a glow, separated the glow from the layer. Treated with difference clouds then brought into PPT and gave it another lightening and added a random bars entry and exit. 

I'd also consider starting with something they see regularly. Like a light switch and a light bulb. Or a garage door and door opener switch. It's not exactly the same mechanic, but the idea is the same. "So it works like a switch? Power goes to the light, power goes to the muscle?" Push the I believe button. 

On the screen, having the illustration for nerve activation and one above it with the lightbulb above the muscle and the switch above the spinal cord with wires going to the bulb. Throw the switch and highlight the nerve lines and the circuit lines.

I meant to add this link as one way you could build an animation / video with masks:

http://www.animatron.com

Thinking about this, maybe this is more of what you're looking for? 

Something like this could be done with motion paths in PPT.