Figure 1

The Stochastic Spike-Diffuse-Spike Model. (a) The action potential shape as it leaves the Ranvier node, schematically indicated in (d). (b) Propagation through the next internode alters the action potential shape as it reaches the next node (black, almost confounded with red). Damage to the internodes will affect this propagation following one of three possibilities. We consider whether demyelination affects the orthodromic internode only (purple), the antidromic internode only (blue) or both internodes equally (red). (c) Probability of transmission as a function of time for the intact and the three cases of damage. (d) Schematic illustration of two Ranvier nodes separated by a distance d for the three damage configurations. For a propagation from left to right, we consider three possibilities for an action potential starting at node (a). Top: demyelination of orthodromic internode. Middle: demyelination of antidromic internode. Bottom: equal demyelination of both anti- and orthodromic internodes