Supplemental Movies

This article contains the following supporting material:

• Movie 1 - Simulated movement of a pulse of 1,000,000 radio-labeled neurofilaments along a nerve for 21 days starting with a 3 mm wide square wave and assuming k_ON=0.01, k_OFF=0.1 and k_REV=0.001. The positions of the neurofilaments were binned into 0.1 mm segments at 0.5 day intervals. The square wave adopts a Gaussian wave form as the neurofilaments move along the axon, reminiscent of the bell-shaped waves observed in radio-isotopic pulse labeling experiments.
• Movie 2 - Simulated movement of a pulse of 1,000,000 radio-labeled neurofilaments starting with a Gaussian wave that approximates the experimental data of Xu and Tung (2000) at day 7 (see Fig. 8) and using the optimized parameters obtained from Fig. 9 (k_ON=0.0175,k_OFF=0.211, and k_REV=0.00012). The positions of the neurofilaments were binned into 0.1 mm segments and sampled at 0.5 day intervals. The wave maintains its Gaussian shape but spreads as it moves distally, closely matching the experimental data at day 21.
• Movie 3 - Graphic representation of the movement of a pulse of 22 neurofilaments in a 200 μm segment of axon over a period of 1 hour using the optimized parameters obtained from Fig.9(k_ON=0.0175,k_OFF=0.211,and k_REV=0.00012). All the filaments are in the same location at the start of the simulation, with 3 on track, 7 in the retrograde state and 15 in the anterograde state. The time readout is in hours, minutes and seconds (hh:mm:ss). The filaments are depicted as 10 μm long bars which are colored black when the filaments are off track and red when they are on track. The thickness of the filaments is not to scale. Note that the filaments spend most of their time off track punctuated by brief periods on track. The filaments move rapidly but the overall speed is slow because they spend most of their time pausing. The net direction of movement is anterograde because the filaments spend more time moving anterogradely than retrogradely. The populations spreads a lot due to the asynchronous and bidirectional nature of the movement and the low frequency of reversals.