The GENSAT project aims to map the expression of genes in the central nervous system of the mouse, using both in situ hybridization and transgenic mouse techniques. It is a collection of pictorial gene expression maps of the brain and spinal cord of the mouse. Using EGFP BAC transgenics, this project provides the scientific community with tools to catalog, map, and electrophysiologically record from individual cells. Our application of Cre recombinase technologies allows for cell specific gene manipulation. The transgenic mice created by this project are available to the scientific community.