To infuse viruses into the NAc, subjects were anesthetized with isoflurane, and holes were drilled bilaterally in the skull at the anterior/posterior and medial/lateral (in reference to bregma) coordinates corresponding to the NAc shell (AP: +1.6 mm, ML: +/−0.78 mm, DV: −7 mm) or NAc core (AP: +1.2 mm, ML: +/−1.9 mm, DV: −6.8 mm) using a 0.3-mm carbide drill bit. Stainless steel tubing (30 g) connected to polyvinyl chloride tubing was filled with 1 μl of virus solution (1 × 1010 to 3 × 1010 TU/ml) using a 10-μl Hamilton gastight syringe. Virus (1 μl) was injected at a rate of 0.1 μl per minute using an infusion pump (Harvard Apparatus, Holliston, MA) for 10 minutes and then allowed to diffuse for an additional 10 minutes. The tubing was removed slowly, and the scalp was closed with sutures. Five days later, daily ethanol self-administration sessions (as above) were continued.
