The main objective of this project funded by the NIH/NIDA is to study expression patterns of sets of genes related to addiction throughout the brain. The gene expression maps created by the Allen Brain Atlas project allowed us to analyze more than 3000 genes at a voxel resolution of 200 microns in the mouse brain. This scale allows one to discriminate between fine anatomical structures in the nervous system (94 of these structures are documented on this website), and supports spatial visualization and comparison of genes at a meaningful resolution.
We developed software tools to compute the similarity between expression patterns of pairs of genes across the whole brain, and to rank individual genes according to how well their expression is localized in a given anatomical structure. We selected approximately 400 genes that have human orthologs, and that are thought to be related to addiction. The software pipeline can easily be adapted to support an expanded set of genes.
The co-expression graphs and localization scores can be exploited to cluster the list of addiction-related genes into smaller lists and to study the relationship between expression of genes and brain regions defined by classical neuroanatomy.