Figure 5.
Bouton output and output endurance are differentially affected by stimulation frequency, bouton size, and Po. Vesicle density is set to 400 μm−3. In each figure row only one of these three parameters were varied, while keeping the other two fixed. Systematic analysis of the effects of changes in Po (A), bouton diameter (d = 2, 3 and 5 μm) with 7, 10, and 14 release sites respectively (B) and stimulation frequency (C) on the simulated total output dynamics over several simulations (dotted) or on derived biophysical depletion laws (lines). If not indicated otherwise we used a Po of 6%, a bouton diameter of 3 μm and a stimulation frequency of 40 Hz. Note that the total bouton output is initially very large at high Po-values, but it rapidly depletes to the output of low-Po boutons that continue reliable transmission. Further note that larger boutons harbor more release sites resulting in larger and longer-lasting total outputs (B). Stimulation frequencies up to 40 Hz can be transmitted reliably over some time (plateaus in C) while higher frequencies can only be maintained for short time periods. Interestingly, the long term behavior is independent on the choice of Po for Po ≥ 5 %.