We have carried out, to the best of our knowledge, the first comprehensive analysis of gene coexpression relationships in human cerebral cortex, caudate nucleus and cerebellum. Our results demonstrate that the transcriptomes of human brain regions are robustly organized into modules of coexpressed genes that reflect the underlying cellular composition of brain tissue. Notably, these modules were identified without making any a priori assumptions regarding the cellular constitution of the tissues analyzed in this study. The elucidation of gene coexpression network organization in the human brain provides a new foundation for neurogenetic inquiries along two primary avenues. First, the identification and characterization of gene coexpression modules constitutes a valuable new resource for context-specific annotation of gene function in the human brain through the oft-invoked principle of guilt by association. Second, the quantitative assessment of module membership provides a new basis for exploring molecular differences that distinguish specific cell types and functional processes in disease and health.
