Cocaine infusions over 10 sessions, in 84 strains of the hybrid mouse diversity panel (HMDP). (A) Infusion means by infusate group, over 10 daily sessions (error bars = SEM, scatter points = strain means). Cocaine taking exceeded saline taking overall; however, intravenous self-administration (IVSA) of either infusate was highly strain-dependent. (B) Correlation heatmap for correlation of infusions across sessions, for cocaine and saline groups. The magnitude of session–session correlation increased in later sessions, indicating stabilization of IVSA