Figure 7.

Bistability in dependence on connection strengths reveals the robustness of the model. Steady-state rates of P (top), B (middle), and A (bottom), for each of the nine connection strengths W_IJ in the rate model. All weights are varied from 0 to 15 pA · s. Solid and dashed colored curves indicate stable and unstable fixed points, respectively. Vertical dashed lines indicate the default values stated in Figure 6A. For all calculations, we have fixed e = 0.5. Further parameters are summarized in Table 5. Since the upper stable branches of P and B in the $P\to P$ connection grow to infinitely high values for a large weight, we show W_PP only in the range from 0 to 3.7 pA · s, above which the numerical continuation of the steady state cannot be made. Except for W_PP, all weights have a critical value separating monostable and bistable regions.