Repeated drug consumption may progress to problematic use by triggering neuroplastic adaptations that attenuate sensitivity to natural rewards while increasing reactivity to craving and drug cues. Converging evidence suggests that glutamate modulation may work to correct these adaptations and rapidly restore motivation for delayed non-drug rewards relative to immediate drug use. Using an established laboratory model aimed at evaluating behavioral shifts in the salience of cocaine now vs. money later, the investigators will test the effect of CI-581a on cocaine self-administration as compared to the active control.