Fig. 6: Calcium release from internal stores is required for BTSP and DDSC.
From: Dendritic, delayed, stochastic CaMKII activation in behavioural time scale plasticity
a, A revised model of BTSP induction. Synaptic inputs activate NMDAR-dependent signalling to prime the stimulated synapses. Combined synaptic inputs and postsynaptic activation of LTCCs lead to delayed plateau potentials. Intracellular Ca2+ release is further facilitated by back-propagating action potentials (BpAPs) and activation of LTCCs. IP3-dependent calcium release from internal stores leads to delayed CaMKII activation (DDSC). DDSC acts as an instructive signal with an extended time window of 20–40 s. PLC, phospholipase C. b,c, Raw EPSP traces (b) (average of ten recordings) before and after BTSP induction and time course of synaptic potentiation (c) in stimulated spines in the presence of nifedipine (Nif), thapsigargin (Thapsi), XestC, U73122 or vehicle (DMSO). d, Summary of magnitude of EPSP potentiation for data in c (DMSO stim, n = 25, adj, n = 24; Thapsi stim, n = 20, adj, n = 18; Nif, n = 13; U73122, n = 13; XestC stim and adj, n = 13). The data are presented as the mean ± s.e.m. Two-way ANOVA (F9,132 = 6.419, P = 1.56 × 10–7) with Dunnett’s multiple comparison test (all P values are shown in the source data file). e, Top, fluorescence lifetime images of a dendrite before, during and after peak CaMKII activity in DMSO, Thapsi, XestC, Nif and U73122. Coloured bar, lifetime (ns). Bottom, representative smoothened dendritic lifetime traces showing DDSC under each condition. Scale bars, 2.5 μm (DMSO, XestC) or 5 μm (Thapsi, Nif, U73122). f, Time course of DDSC onset frequency under each condition. g, Cumulative histogram of f. Two-sided Kolmogorov–Smirnov test with Bonferroni’s correction for DMSO versus Thapsi, P = 7.4 × 10–11; DMSO versus XestC, P = 2.2 × 10–13; DMSO versus Nif, P = 4.3 × 10–12; and DMSO versus U73122, P = 7.4 × 10–11. BTSP data from Fig. 3 are also shown (light grey). h, Representative traces of ER-GCaMP6-210 experiments in cells treated with DMSO, XestC or U73122. i, Representative dendrite of a cell expressing the ER-GCaMP6-210 sensor with EPSP traces (bottom) showing successful BTSP induction. Scale bar, 5 μm. j, Time course of frequency of Ca2+ release events under no stim (brown), stim (DMSO), XestC and U73122 conditions. k, Cumulative histogram of j. Two-sided Kolmogorov–Smirnov test with Bonferroni’s correction for DMSO versus no stim, P = 0.0003; DMSO versus XestC, P = 0.0003; DMSO versus U73122, P = 0.000003. Number of cells or dendrites are mentioned in the panels in parentheses wherever appropriate. Plus symbol in images depict the BTSP-stimulated spine. **P < 0.01, ***P < 0.001.
