Fig. 2.

Four bifurcation scenarios with decreasing $v_c$ in the 4-dimensional model when different values are chosen for $g_{kv}$. a Case-1: a bifurcation scenario proceeds from period-adding bifurcation without chaos to bursting with multiple spikes, to spiking via the shrinkage of ISI, and at last to period-1 spiking when $g_{kv}=1490\text{pS}$; b Case-2: a bifurcation scenario proceeds from a period-adding bifurcation with chaos or from a period-doubling bifurcation to chaos, to bursting with multiple spikes, to spiking via shrinkage, and at last to period-1 spiking when $g_{kv}=1600\text{pS}$; c Case-3: Period-1 bursting changes to period-2 firing, then to period-1 spiking when $g_{kv}=1665\text{pS}$; d Case-4: period-1 bursting changes directly to period-1 spiking when $g_{kv}=1680\text{pS}$