To gain further insight into the observed reduction in responding, we chose four sessions in which to analyze the pattern of responding within the test session in 5-minute bins (Fig. 2). While there were significant main effects of session time for the baseline session (F(5,110) = 24.28, P < 0.001; Fig. 2a), and both day 5 (F(5,110) = 15.94, P < 0.001; Fig. 2b) and day 30 (F(5,110) = 31.75, P < 0.001; Fig. 2d) after virus infusion, there were no main effects of treatment or any treatment by session time interactions (F < 1). However, responding on day 18 was significantly altered after GABAAR α4 subunit knockdown. For day 18, there was a main effect of time (F(5,110) = 25.56, P < 0.0001) and virus treatment (F(1,110) = 19.47, P < 0.001), and a significant interaction between treatment and time (F(5,110) = 2.6, P < 0.05; Fig. 2c). These effects were accounted for by a significant decrease in active lever responding by the Ad-shα4 group 5–10 minutes (P < 0.01) and 10–15 minutes (P < 0.05) after session onset,
