Extended Data Fig. 2: Contact sizes and reproducibility.
From: A multi-scale brain map derived from whole-brain volumetric reconstructions
a–f, Small membrane contact areas are less likely to be bilaterally conserved. Membrane contacts were divided into three groups (‘low’, ‘mid’ and ‘high’) on the basis of their membrane contact areas (35% low, 31% mid, 34% high; see Supplementary Results). a, Similarity of homologous (L4 bilateral; adult bilateral; L4 and adult—same side) immediate neighbourhood compositions for low, mid and high membrane contact groups, as measured by the Jaccard index (Supplementary Results; n = 80 cell classes). Box plots: centre line, median; box limits, upper and lower quartiles; whiskers, 1.5 × interquartile range; points, outliers. b, c, Survival (that is, complementary cumulative) distribution of membrane contacts in the adult nerve ring (b, n = 5,179) and the L4 nerve ring (c, n = 4,744). The pie charts show the fraction of total membrane area contact between all processes accounted for by each group. d, Empirical frequency distribution of synaptic (n = 2,433) and gap-junctional (n = 573) contacts broken down by the reproducibility of membrane contacts. The majority of synaptic contacts (77% and 85% of synaptic and gap-junction contacts, respectively) occur at M4 contacts. e, f, Cumulative distribution of ℂδ synaptic contacts (e) and Gδ gap-junction contacts (f) for δ = 1, 2, 3, 4 as a function of membrane contact area (in percentiles). To control for differences in neurite placement, we restrict ℂδ and Gδ to contacts that occur on M4 membrane contacts. The smallest 35% of membrane contacts (dashed line) encompass around 3% of ℂ4 synaptic contacts and around 9% of G4 gap-junction contacts (on M4) with growing fractions for smaller δ (up to around 33% and around 27% of the more variable ℂ1 and G1 contacts). g, Empirical frequency distribution of membrane, synaptic and gap-junctional contacts across the four datasets (δ = 1 to 4). h–j, Survival distribution of contacts as a function of membrane contact area for Mδ (h), ℂδ (i) and Gδ (j) graphs (n given in g), plotting the probability that a membrane, synaptic, or gap-junction contact occurs with a membrane contact area that exceeds some value. Membrane contact areas have been log-normalized and standardized so that the distribution is centred about 0, that is, log-transformed, standardized (by subtracting the mean) and normalized (by dividing by the standard deviation), such that a range of ±1 corresponds to ±1 standard deviation of the distribution of log(membrane contact area).
