Bifurcation diagrams of ML model neuron for variable bias current at high (a) and low (b) calcium conductances, respectively. For large , stable limit cycle oscillations emerge at low bias currents through a SNIC bifurcation (point ) and through Andronov-Hopf (HB point) for large bias currents (a). The stable oscillations that emerge in a SNIC-HB diagram have a PRC that is a linear combination of a pure Type I PRC (characteristic to SNIC bifurcation) and pure Type II PRC (characteristic to HB). At smaller calcium conductance, the two limit points and of the SNIC bifurcation collapse into a HB point and a HB-HB diagram emerges (b). The peak-to-peak amplitude of oscillations in a HB-HB diagram is smaller than that in a SNIC-HB diagram due to a reduce activation of calcium channels and the fact that the dynamics of the system are dominated by the outward potassium current. As a result, in a HB-HB system the bias current is larger than that in the case of a SNIC-HB system to compensate for the larger outward potassium current.