Figure 5.

The extended binomial model captures the relation between the CVs and the EPSP amplitudes over the whole range of amplitudinal response. The CVs of the synaptic responses from the 20 connections were plotted vs. their mean EPSP amplitudes (on a log-log scale, black dots), grouped by the stimulus’ index along the pre-synaptic spike train. In red are the corresponding CVs as predicted by the extended binomial model: ${\text{CV}}^{\text{μ}}=\sqrt{1/M^{\text{μ}}}\cdot \sqrt{q\cdot (1-U^{\text{μ}})},$ where M is the EPSP amplitude as measured in experiments, q is the computed quantal size and U^μ = U·ρ^μ is the effective probability of release for the μth response (with ρ¹ = 1, see Eq. 14).