Fig. 1.

Mapping the transcriptional signature of large-scale brain network topology. (A) Defining highly connected hub regions with connectivity degree $k>44$, all neuronal connections between each of 213 brain regions were labeled as rich (hub $\to$ hub; red), feeder (hub $\to$ nonhub or nonhub $\to$ hub; green), or peripheral (nonhub $\to$ nonhub; blue). (B) Network schematic illustrating the different connection types in the mouse brain. (C) Normalized expression levels of 17,642 genes (columns) measured in each brain region (rows) visualized here using color from low (blue) to high (red) are used to compute the correlation in expression profiles or gene coexpression for each pair of brain regions. Missing data are shown as green, and columns of the matrix have been reordered using hierarchical clustering to place genes with correlated expression patterns close to one another.