Figure 1

(A) A presynaptic perturbation (vertical arrow) delivered at stimulus time t_s changes the intrinsic firing period T_i to T₁, T₂, T₃, … The unperturbed activity (dashed line) is shifted (reset) due to an external perturbation. (B) In a two-neuron network, when neuron “2” fires (solid rectangle), it perturbs neuron “1” at a stimulus time t_s1[n-1], during (n-1)^th cycle. In turn, neuron “1” recovers from that perturbation and fires again after T₁[n-1] perturbing neuron “2” at stimulus time t_s2[n]. (C) In its canonical form, the PRC of a Type I excitable cell only depends on the strength of coupling between cells and the intrinsic firing periods, which leads to a four-dimensional parameter space for a two-neuron network: (c₁, c₂, T₁, T₂). The recursion (1) predicts the steady phase locked mode.