Fig. 7.

Propranolol impairs delayed extinction. In contrast to its effects on immediate extinction, propranolol given 30 min before a delayed extinction session, which took place 24 h after conditioning (A) did not significantly alter within-session extinction (B). Moreover, propranolol-treated rats exhibited a deficit in extinction recall 24 h after extinction (C) (vehicle, n = 8; propranolol, n = 8). Gray bars denote the 3-min baseline (BL) period before delivery of conditioning or extinction trials. *P < 0.05 vs. vehicle. All values are means ± SEM.