Extended Data Fig. 3. Core and variable model validations.

a,b, Model fits for reproducibility of ${\mathbb{M}}^{\delta }$ contacts, with membrane contact areas a, below and b, above the log-normalized mean (after thresholding, Methods, Extended Data Fig. 2h). c,d, Reproducibility model fits of c, inter-cluster and d, intra-cluster ${\mathbb{M}}^{\delta }$ contacts. e, Reproducibility model fits for complete ${\mathbb{M}}^{\delta }$, ${\mathbb{C}}^{\delta }$ and ${\mathbb{G}}^{\delta }$ datasets including membrane contact areas <35% (results qualitatively similar to restricted dataset model fit in Figure 2a; Methods: Generating reference graphs). f, Reproducibility model fits for ${\mathbb{C}}^{\delta }$ excluding synaptic contacts scored in only 1 EM section (Methods). g, Reproducibility model fits for ${\mathbb{C}}^{\delta }$ excluding synaptic contacts derived from non-reproducible post-synaptic partners of polyadic synapses (Methods). h,i, Reproducibility model fits for synaptic and gap junction contact datasets scored by h, White et al. (1986)⁵ and i, Witvliet et al. (2020)²⁰ limited to our ${\mathbb{M}}^4$ contacts. $\mathbb{M}$: membrane, $\mathbb{C}$: chemical synapse and $\mathbb{G}$: gap junction contacts. Black bars: empirical distributions used in this study. Gray bars: other empirical distributions^5,20. Red bars: Model fits for the empirical distributions. All fractions of the total empirical counts ($n$).