Figure 7. The model can display bistability, sustained oscillations, stable high or low levels of Hes1 depending upon its parameterization.

Local bifurcations are shown for changes in the miR-9 degradation rate, μ_r, the strength of repression of miR-9 production by Hes1, p₁ and the shape of repression of miR-9 production by Hes1, n₁. The presence of Hopf and fold bifurcations are indicated by blue and red solid lines, respectively. Fold bifurcations lead to the creation or elimination of a pair of fixed points. Blue regions, therefore, indicate the presence of oscillations, while red regions indicate bistability. White regions represent the case of a single steady state with either high or low Hes1 levels (as indicated by the annotation). (a) n₁=1. (b) n₁=5. Other parameters are p₀=390, τ=29 min, b_l=ln(2)/20 min⁻¹, b_u=ln(2)/35 min⁻¹, n₀=m₀=m₁=5, r₀=100, r₁=300, μ_p=22 min.