Figure 1.
Transition from stochastic population asynchrony to SPO in a Type 2 neuron with increasing bias current. A, Stochastic population asynchrony (Iext = 0.4 nA). A1, ISI histogram. A2, Spike time histogram. A3, Raster plot (down sampled 71 neurons out of 3,000). A4. Current relative to bifurcations [red dashed lines, AH Andropov–Hopf, SNP saddle node of periodics, total synaptic input current averaged over the network (green), and mean current for single neurons (dark blue)]. Single neuron voltage trace (light blue). B, Emergence of SPO at the Hopf bifurcation (Iext = 1 nA). B1–4 as in A1–4. Spikes per cycle (SPC) is 0.49. C, Beyond the Hopf, the oscillation amplitude increases (Iext = 1.6 nA). C1–4 as in A1–4. In all the three cases the synaptic strength is 7.94 nA and the noise intensity is 3.16 nA. SPC is 0.59. All units are given per cm2.