Fig. 6.

A: 3 gain functions are considered: f(x) = ${\sqrt{\left[x\right]}}_{+}$ (see Eq. 8) with a sharp threshold at x = 0, f(x) = ${\sqrt{\left[x\right]}}_{*}$ (see Eq. 11) with c = 0.01 (less smoothing), and f(x) = ${\sqrt{\left[x\right]}}_{*}$ with c = 0.05 (more smoothing). Compare the shape of the square root function with the sigmoid (inset), which was used for Fig. 4, A and B. B: period-input curves for f(x) = ${\sqrt{\left[x\right]}}_{*}$ and adaptation only. C: period-input curves for f(x) = ${\sqrt{\left[x\right]}}_{+}$ without input noise (black curve) and with input noise (gray curve, σ = 0.05).