Calcium modeling of spine apparatus-containing human dendritic spines demonstrates an “all-or-nothing” communication switch between the spine head and dendrite
Fig 3
Effects of passive spine SA on spine-to-dendrite Ca2+ signaling, with fixed Ca2+ influx. Row A, without SA, and row B, with SA, show [Ca2+] profiles for 10 ms initial Ca2+ release into the spine head. Consistent with experimental data, spine-to-dendrite Ca2+ signaling does not occur for all 9 simulated spines, and this also holds true for simulations where Ca2+ influx is adapted to the postsynaptic area, see additional plots. Row C (fixed Ca2+ influx) demonstrates correlations between maximum [Ca2+] in the head region versus spine volume, ratio of SA area/Spine area, and SA volume/Spine volume. Presence of a passive SA, i.e., no ryanodine receptors, has no major effect on [Ca2+] dynamics in the spine head and neck.