Fig. 6

Left: three-dimensional [3D] projections of three bursting orbits passing by the saddle. An extra spike is gained by the orbit after it has switched the outgoing directions determined by the unstable separatrices of the saddle. (A)-(D) Waveforms of four bursting orbits, shown in the phase space of the model on the left, at spike-adding or deletion bifurcations for the indicated parameter values of I and b.