Rats (ST, n = 8; IN, n = 8, GT, n = 12) were first trained using standard 5-d conditioning procedures as described above. The next week, rats were anesthetized (ketamine, 100 mg/kg; xylazine, 10 mg/kg; IP) and underwent stereotaxic surgery for in vivo FSCV. As previously described (Vander Weele et al. 2014 (link); Singer et al. 2016 (link)), a guide cannula (Bioanalytical Systems) was implanted dorsal to the NAc core (AP, +1.3; ML, ±1.3; DV, −2.5 mm relative to bregma) and an Ag/AgCl reference electrode was secured in the contralateral cortex (AP, −0.8; ML, ±4.0; DV, −2.0 mm relative to bregma). In addition, a bipolar-stimulating electrode (AP, −5.2; ML, ±0.8 mm relative to bregma; Plastics One) was lowered into the ventral tegmental area (VTA) until electrically evoked DA release was able to be measured in the striatum. DA release was recorded using glass-encased cylindrical carbon-fiber electrodes. Surgical screws and dental acrylic were used to secure cannula and electrodes in place. Before surgery and during recovery, rats were administered saline, the antibiotic cefazolin (100 mg/kg, SC), and the analgesic carprofen (5 mg/kg, SC).