Decreases in instrumental responding for ethanol after GABAAR α4 subunit knockdown in the NAc shell occurs after session initiation. Within-session responding during 30-minute sessions by the same subjects depicted in Fig. 1 during the final session prior to virus infusion (a; baseline) and during day 5 (b), day 18 (c) and day 30 (d). (c) Responding by Ad-shα4-treated rats was significantly decreased on day 18 at the 5–10 and 10–15 minutes intervals (*P < 0.05, **P < 0.01, Ad-shα4 versus Ad-NSS groups) but not during the first 5 minutes of the session. There were no group differences during the baseline session or days 5 and 30 (a, b, d). Values depict mean +/− SEM of active lever responses within 5-minute bins. Data are presented as mean +/− SEM. n = 12 rats per group