Multiscale modeling of presynaptic dynamics from molecular to mesoscale
Fig 2
Spatial Modeling of Spike-Evoked Ca2+ Transients.
(A) Ca2+ sensors (dark yellow through dark blue filled circles) at vesicle cluster centers, displaced linearly from cluster of Ca2+ channels (blue half-disk on the left); distance in μm, dn = 0.160+0.105n for n∈{0,…,16}. (B) [Ca2+]i measured over time in MCell (dark yellow through dark blue) and in the deterministic well-mixed model (maroon). MCell traces averaged from 2000 trials of MCell simulations with Δt = 0.1 ms. Color transitions from yellow for vesicles proximal to the VDCC Ca2+ source to blue for vesicles far away, as in A. Proximally (distally) measured [Ca2+]i displays more (fewer) components of decay than are evident in the deterministic model. (C) Logarithmic plots of peak [Ca2+]i (blue) and peak time (red) as a function of distance from Ca2+ source; peak [Ca2+]i drops off exponentially with distance from VDCC cluster; amplitude of latent Ca2+ dominates over the initial action-potential-evoked influx after 1.4 μm.