Fig. 1: Model of the presynaptic vesicle cycle.
A Model of the presynaptic vesicle cycle, as proposed in14. Vesicles transition stochastically from pool to pool with a given timescale. Timescales of transitions are taken from experimental measurements14 (see SI) and become orders of magnitudes larger the further they are away from the release stage (Primed pool). Similarly, the maximum number of vesicles in pools (numbers in circles) is larger for pools farther away from release. Upon an input spike, vesicles in the primed pool are emitted with probability pfuse. Subsequently, vesicles can age with probability page and are dynamically resupplied if the synapse lacks vesicles. Since the ageing and supply processes are very slow (order of hours) they have limited significance for the analysis in this work. B, C (top) Example of how spikes (red) result in the release of vesicles (blue) and (bottom) how vesicle pool levels change over time. Pools close to release operate on a fast timescale (B), whereas pools far away operate on slow timescales (C).
