Fig. 3From: Neural Excitability and Singular BifurcationsNeural model (1): nullclines under variation of I which leads to the (singular limit) definition of \(I_{\mathrm{bif}}\): (Type I) \(I=I_{\mathrm{bif}}\) at a saddle-node bifurcation; (Type II) \(I=I_{\mathrm{bif}}\) at (singular) Andronov–Hopf bifurcation. In the transition from type II to type I, a cusp bifurcation appears as can be predicted by looking from the bottom pictures in this figure Back to article page