Fig 9. The model KO cell can produce bursting with upregulation of a constant-conductance (leak) K+ current and a K(Ca) conductance: gleak = 32.5 pS, gK(Ca) = 90 pS.
(A) Negative feedback of c (black) on the membrane potential and slow cer (blue) oscillations drive bursting. (B) The fast-subsystem bifurcation diagram exhibits an interval of bistability between the saddle-node bifurcation SN2 and the homoclinic bifurcation HC. (C) A projection of the burst trajectory. (D) Fast/slow analysis, with the burst trajectory (red) and the cer nullcline (magenta) superimposed on the fast-subsystem bifurcation diagram. The trajectory moves leftward during the silent phase and rightward during the active phase.