Fig. 3: Influence of synaptic configuration on postsynaptic Ca2+ signals in dendrites. | Nature Communications

Fig. 3: Influence of synaptic configuration on postsynaptic Ca2+ signals in dendrites.

From: Intracellular magnesium optimizes transmission efficiency and plasticity of hippocampal synapses by reconfiguring their connectivity

Fig. 3

a Left, spine Ca2+ influx (GCaMP+) and Pr (FM5-95+) of synapses. Right, integrated spine Ca2+ (wCa) against Pr (n = 101, 127 synapses from 3, 3 repeats). Curve fitting, wCa = 31.10•Pr0.55–3.95 (R2 = 0.76). b Left, GCaMP+ dendrites. Right, box magnification. Pseudo-color, integrated ΔF/F0. White/red arrows, low/high-Ca2+ spines. c Left, synapse density (D) against \(\overline{{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}\) in dendrites (n = 24, 23 branches from 3, 3 repeats; hyperbolic fitting, R2 = 0.80). Top-right, D versus 1/\(\overline{{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}\) (linear regression, R2 = 0.81, P < 0.0001). Bottom-right, total wCa (ΣwCa) versus \(\overline{{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}\) (linear regression, R2 < 0.0001, P = 0.97). d Shifted wCa distribution (n = 193, 156 spines from 4, 3 repeats; two-sided Kolmogorov–Smirnov test, ****P < 0.0001). wCa(-), no Ca2+ influx. Dashed line, wCa = 15. e Integrated burst-evoked Ca2+ (\({{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}_{{{{{{\boldsymbol{burst}}}}}}}\)) against wCa in single spines (n = 59, 81 spines from 3, 3 repeats). Dashed line, bisector. Inset, ΔwCa (=\({{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}_{{{{{{\boldsymbol{burst}}}}}}}\)-wCa) against wCa. Curve/error band, mean/SEM. f Relationship between D, \(\overline{{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}\), ΣwCa and Σ\({{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}_{{{{{{\boldsymbol{burst}}}}}}}\) at dendrites (n = 24, 23 branches from c). g Comparison of ΣwCa and Σ\({{{{{{{\boldsymbol{w}}}}}}}_{{{{{{\boldsymbol{Ca}}}}}}}}_{{{{{{\boldsymbol{burst}}}}}}}\) of individual branches (n = 24, 23 branches from f; two-sided Kolmogorov–Smirnov tests, P = 0.73, ****P < 0.0001). h Top, evoked spine Ca2+ before and after GluN2B blockade. Traces, averaged 30 sweeps from 441 spines. Bottom-left, integrated Ca2+ (n = 441 spines from 7 repeats; two-sided Kolmogorov–Smirnov tests, ****P < 0.0001). Bottom-right, percentages. i Plot of q’NMDAR (=wCa/Pr) against Pr (n = 101, 127 synapses from a). Inset, distribution (two-sided Kolmogorov–Smirnov test, ****P < 0.0001). Curve fitting, wCa /Pr = 20.25•(1/Pr)0.43 (R2 = 0.18). j Left, juxtaposed FM5-95+ boutons and GluN2B-GFP+ spines. Arrowheads/asterisks, high-Pr–low-[GluN2B] or low-Pr–high-[GluN2B] synapses. Right, spine [GluN2B] versus Pr (n = 102, 110 synapses from 3, 3 repeats). Inset, [GluN2B]Sp distribution (two-sided Kolmogorov–Smirnov tests, ****P < 0.0001). Curve fitting, [GluN2B]Sp = 0.0987•(1/Pr)0.45 (R2 = 0.16). In (a, c, i, j), blue lines and error bands, fitted curves and 95% CIs. In (g, h), box borders/line, quantiles/median; whiskers, min/max. Source data are provided as a Source Data file.

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