Figure 4.

Nearly-singular periodic orbits perturb to continuous spiking or mixed mode oscillations. In both cases g_BK = 0.4 nS, and g_K = 5.1 nS in the left column, g_K = 4 nS in the right column. C_m is increased from top row to bottom row. (a), (c), (e) The singular periodic orbit does not enter the singular funnel (δ < 0) so it perturbs to continuous spiking. (b), (d), (f) The singular periodic orbit enters the singular funnel (δ > 0) so it perturbs to mixed mode oscillations or pseudo plateau bursting.