Fig. 20

Real paths. This a flat projection of the unfolding of the focus case (same projection as in Fig. 9). We added the projection of the paths used for the bifurcation diagrams in Fig. 6 and the simulations in Fig. 8. The black portion of the path is where bursting takes place (i.e. where the slow variable oscillates). The gray part is the additional portion of the great circle explored to create the bifurcation diagrams in Fig. 6