significantly occupied by ΔFosB under saline and cocaine-treated conditions independently. After pre-processing and normalization, we generated a high-confidence gene list at a false discovery rate of 5% using established methodology (see Supplemental Methods). In chronic cocaine-treated mice, ΔFosB was bound to nearly 40% more promoters (1553) than it was in saline-treated mice (1113) (see Supplemental Tables S6 and S7), which is consistent with the several fold induction of ΔFosB in the NAc by cocaine (Nestler, 2008).