This animation was created with the help of a few javascripts I wrote for Softimage XSI back in 2006. The first script would go down the length of the neuron and generate a curve within it. A second script would allow the user to select a group of curves and then generate null objects that would travel down the length of the curve. The percentage of the null objects' journey down the curve was controlled by a GUI with sliders, also generated by the script. Another script would link the null objects to the Neurons' surface shader and generate a glow based on the distance of the null object's center to the surrounding neuron's geometry. My coworkers handled the camera movement and the finer points of the rendering and compositing.
Mark Bamforth