Fig. 2. Influence of synaptic configuration on excitatory synaptic transmission in dendrites.

a Left, confocal images to show juxtaposed FM1-43⁺ and GluA2*AMPAR⁺ puncta at example dendritic segments. Right, synaptic [GluA2] against Pr in single synapses (n = 140, 167 synapses from 3, 3 repeats; linear regression, R² = 0.34, P < 0.0001). Inset, shifted synaptic [GluA2] distribution (two-sided Kolmogorov–Smirnov test, ****P < 0.0001). b Left, plot of D against the mean [GluA2] ($\overline{\left[\mathrm{GluA2}\right]}$) of synapses at dendritic branches (n = 26, 42 branches from 3, 3 repeats; hyperbolic fitting, R² = 0.52). Top right, D against 1/[GluA2] (linear regression, R² = 0.55, P < 0.0001). Bottom right, total [GluA2] (Σ[GluA2]) against $\overline{\left[\mathrm{GluA2}\right]}$ (linear regression, R² = 0.018, P = 0.28). c, d Similar to (a, b), but immunostaining for PSD95 (n = 210, 163 synapses from 4, 3 repeats for c; 65, 62 branches from 4, 4 repeats for d). Two-sided Kolmogorov test (c, inset), **P = 0.0019. Linear regressions (c, d), R² = 0.52, 0.55, 0.046, P < 0.0001, <0.0001, = 0.0150. Hyperbolic fitting (d, left), R² = 0.40. e Formulas for estimating quantal size (q’), synaptic weight (w’) and bursting synaptic weight (w’_burst) of single synapses, as well as total basal strength (G’) and total bursting strength (G’_burst) of dendritic branches. f The relationship between D, $\overline{\mathit{q}’}$ and G’ (left; n = 65, 62 branches from 4, 4 repeats) or G’_burst (right; n = 49, 56 branches from 3, 3 repeats) (coded by pseudo color) at individual dendritic branches (data from separate measurements). Insets, G’~$\overline{\mathit{q}’}$ and G’_burst ~ $\overline{\mathit{q}’}$ associations. The $\mathit{q}’$ of individual synapses was estimated by postsynaptic [PSD95]. g Box-whisker plot of G’ and G’_burst from physiological and elevated Mg²⁺ conditions (n = 65, 62, 49, 56 branches from 4, 4, 3, 3 repeats; the same data as in f). Box borders/line, quantiles/median; whiskers, min and max. Two-sided Kolmogorov–Smirnov tests, **P = 0.0016, *P = 0.0162. In (a–d), blue lines/error bands, fitted curves/95% CIs. Source data are provided as a Source Data file.