Figure 4.

The ratio between extrinsic and intrinsic noise, ΔCa^∗/σ_c, determines the range of robustness. (A and B) the relative amplitude of the PF input, x, dependency of ΔCa^∗/σ_c with μ_a = 180 in the spine volume (A) and in the cell volume (B) are provided. The robustness index δ_max is defined as x giving ΔCa^∗/σ_c = 1. (C) The volume-dependency of δ_max for μ_a = 180 is provided. (D) The relationship between ΔCa^∗/σ_c and the χ² distance between the averaged distribution of the distributions of Ca_res with Amp_PF = μ_a ± x and the distribution of Ca_res with Amp_PF = μ_a are provided. The red points, blue points, and gray dots indicate the value obtained in the spine volume, the cell volume, and the intermediate volumes, respectively. To see this figure in color, go online.