Responses (mean/2 h+SEM) on the active (a) and inactive (b) levers during self-administration (SA; last 3 days of training), extinction training (EXTb, last session before the extinction context test), as well as during testing conducted in the extinction (EXT CTX) and cocaine-paired contexts (COC CTX). Microinfusions of B/M (black bars; 1.0/0.1 mM, 0.3 μl per site) or Veh (open bars; 0.3 μl per site) were administered into the NAC core (N=8–10 per group) or shell (N=8–9 per group) immediately before each test session. In the main panel, symbols represent significant difference relative to the extinction context test (asterisk, ANOVA context simple main effect, p=0.0001), relative to Veh treatment (cross, ANOVA treatment simple main effect, p=0.002–0.045), and relative to EXTb (double cross, ANOVA day simple main effect, p=0.03). In the insets, symbols represent significant difference relative to the extinction context test (number sign, ANOVA context simple main effect, p=0.002–0.01) and relative to Veh treatment (carat sign, a ANOVA treatment simple main effect, p=0.04; b ANOVA treatment main effect, p=0.001)