We are the cumulative product of past experiences, which define our interaction with the world. Experiences leave their mark, at least in part, through the induction of immediate-early genes (IEGs) within neuronal assemblies. However, the rules governing the distribution of IEG expression within neuronal assemblies have not been comprehensively studied. To identify these rules, we applied a technique that enables quantitative measurement of the expression of multiple genes within single neurons, and studied the encoding of cocaine experience in the striatum, a region of the brain associated with drug addiction. We identified principles governing the induction of gene expression and report region-specific rules defining cell-specific recruitment. Our results suggest the existence of “super-ensembles” of neurons found in spatially defined clusters and characterized by the coherent and robust expression of multiple IEGs.