Figure 8. Dynamically equivalent effects of varying other model parameters in the 2-D model.

Effects of changing β_w (A), g _fast (B), g _slow (C), and β_m (D) in the original 2-D model. All parameters were at their default values (see Methods) except for the parameter of interest, which was varied from its default value (green) to a value causing neuropathic excitability (red) as indicated on each panel. In each case, the shape and/or positioning of the V- or w-nullcline (shown on phase planes; left panels) was affected in a distinct way, but the geometry of the nullcline intersection showed the equivalent “neuropathic” change, as evidenced by the bifurcations diagrams (right panels); specifically, all “neuropathic” bifurcation diagrams exhibit a Hopf bifurcation. For A–D, the “normal” bifurcation diagrams are equivalent and correspond to that shown in Fig. 2B top.