Fig. S3.

Relationship between gene coexpression, connectivity, and separation distance in the mouse connectome. All pairs of brain regions i and j (excluding self-connections, $i\ne j$) were classed as (i) reciprocally connected pairs of brain regions if both $i\to j$ and $j\to i$ (orange), (ii) unidirectionally connected pairs of brain regions if either $i\to j$ or $j\to i$ (but not both; green), or (iii) unconnected pairs if neither connection is present (blue). (A) Distributions of gene coexpression for each of the above types of interregion pairs. (B) Gene coexpression, $G_{ij}$, as a function of Euclidean distance of separation, $d_{ij}$, for all interregion pairs, with a fitted exponential decay as labeled. (C) Distributions of gene coexpression for all classes of interregion pairs after correcting for the exponential distance relationship shown in B. Both before and after correcting for spatial correlation in the data, pairs of reciprocally connected brain regions have the highest gene coexpression followed by unidirectionally connected brain regions and unconnected brain regions; P values from Welch’s t tests are annotated to A and C.