Inferring synaptic transmission from the stochastic dynamics of the quantal content: An analytical approach
Fig 2
Transient reduction in quantal content (QC) is associated with an increased QC Fano factor.
A) The average QC, i.e., the average number of synaptic SVs fusing per AP as predicted by Eqs 5 and (10) for a constant release probability pr = 0.15 (blue, orange, and gray dots), and undocking probability pu = 0. To capture synaptic facilitation (yellow dots) we also consider a time-varying release probability: pr,1 = 0.15 (first stimulus), pr,2 = 0.2 (second stimulus), pr,3 = 0.25 (third stimulus) and pr = 0.3 for the fourth and all remaining stimuli. The number of docking sites M = 200 are all assumed to be filled upon arrival of the 1st AP. The per-site SV refilling probability is pd = 0.3 (blue dots), 0.15 (orange dots), 0.05 (gray dots), or 0.02 (yellow dots). B) The corresponding QC Fano factor FFi over time as predicted by (7).