Multiscale modeling of presynaptic dynamics from molecular to mesoscale
Fig 9
Empirical Facilitation in Synchronous and Asynchronous Release Rates.
Release rate profiles facilitate in response to single spikes (A) or to spike ramps (B,C). Probe spikes of increasing ISI reveal how facilitation then decays back toward baseline after a delay. Each rise in release rate is triggered by a spike event. Synchronous release rate profiles shown in blue. Asynchronous profiles shown in red. Profiles from multiple runs are overlaid in each panel. Dark colors represent response to initial spike or spike ramp (common to all traces on a plot). Light colors represent profiles from different runs in response to single probe spikes at different ISIs following the initial spike or ramp. (A) After single spike, paired-pulse facilitation decays with increasing ISI (probe ISIs of 2, 5, 10, 20, 50, 100, 200 ms). (B) 5-spike ramp with a 5-ms ISI shows strong facilitation in release rate (dark colors) followed by rapid decay seen at the probe spikes (light colors). (C) 5-spike ramp with a 20-ms ISI shows weaker facilitation in the ramp phase but a similar rate of decay at the probe spikes. Note the orders of magnitude difference in scale between synchronous and asynchronous release rates, as well as the change in scale from (A) to (B,C).