Fig. 4

Deterministic phase plane dynamics (adapted from [114]). Thick curves show the nullclines: \(\dot{v} = 0\) as grey and \(\dot{w}=0\) as black. Black stream lines represent deterministic trajectories. Green/blue curves represent an action potential trajectory in the limit of slow w. Parameter values are \(C_{m}=20~\mbox{mF}\), \(V_{\mathrm{Ca}}=120~\mbox{mV}\), \(V_{\mathrm{K}}=-84~\mbox{mV}\), \(V_{\mathrm{L}}=-60~\mbox{mV}\), \(g_{\mathrm{Ca}}=4.4~\mbox{mS}\), \(g_{\mathrm{K}}=8~\mbox{mS}\), \(g_{\mathrm{L}}= 2.2~\mbox{mS}\), \(\beta_{\mathrm{Ca}}=0.8~\mbox{s}^{-1}\), \(v_{\mathrm{Ca}, 1}=-1.2~\mbox{mV}\), \(v_{\mathrm{Ca},2}=18~\mbox{mV}\), \(v_{\mathrm{K},1}= 2~\mbox{mV}\), \(v_{\mathrm{K},2}=30~\mbox{mV}\), and \(\phi=0.04~\mbox{ms}^{-1}\)