Figure 1

The firing rate of a bistable unit evolves under constant stimuli (red bars) with different durations and amplitudes. The final states depend on initial states, amplitudes, and durations, with symbol “+” standing for the ON state and “–” for the OFF state. Panels (a1)–(b1), marked by a down-triangle, show no history dependence. Panels (a2)–(b2), marked by a star, show maximal history dependence. Panels (a3)–(b3), marked by an up-triangle, again show no history dependence as the final state is independent of the initial state. Panels (a4)–(b4), marked by a circle, show the trivial history dependence of a bistable system, as with the amplitude halved from that used in (a3) and (b3) the stimulus causes no change in state. These markers correspond to different regions in the phase diagram [see Fig. 2(a3)–(a4)]