Figure 1
From: Periodically stimulated piecewise linear adaptive exponential integrate-and-fire neuron

(A) Various bifurcations shown in 1:1 phase locked solutions. PD: Period-doubling; sn1: saddle-node in switching manifold once; sn3: saddle-node in switching manifold three times, 1 → 3, transition from sn1 to sn3. (B) Frequency mode locked solutions shown in the marked Arnol'd tongue structure.