Figure 2.

mGluR5-mediated facilitation of the extinction of ethanol self-administration represents new learning. A, Analysis of within-session responding during the first day of extinction revealed a treatment × time period interaction (n = 11). B, Comparison of the binned responses revealed that CDPPB did not alter responding on the previously active lever during the initial 3 min of the extinction session, but did significantly reduce responding on this lever during the remainder of the extinction session (*p = 0.005). C, In contrast, analysis of the second day of extinction training revealed a significant group difference during the first 3 min of the extinction session, with CDPPB-treated animals responding significantly less during this time period. *p = 0.013.