To assess the transcriptional relatedness, we calculated correlation matrices of pairwise comparisons between brain regions/NCX areas (Fig. 1c) and performed unsupervised hierarchical clustering across periods 3–15, when all analyzed regions/areas can be consistently followed across time. Among regions, this analysis showed distinct and developmentally regulated clustering of NCX (combination of 11 areas), HIP and AMY, with CBC exhibiting the most distinctive transcriptional profile. At the level of NCX areas, clustering formed the following groups during fetal periods: OFC, DFC, and MFC of the prefrontal cortex; VFC and primary somatomotor cortex (S1C and M1C); and parietal-temporal perisylvian areas (IPC, A1C, and STC). V1C had the most distinctive transcriptional profile of NCX areas throughout development and adulthood. The increased correlations between NCX, HIP, AMY, and the majority of non-V1C NCX areas with age indicate that transcriptional differences are particularly pronounced during development.
