Figure 1.

Blockade of noradrenergic β-receptors in IL impairs extinction memory. A, The photomicrograph shows a representative guide cannula tract (arrow indicates injector tip). Coronal drawings (bregma, +3.20 mm) show placements of injector tips for all rats in IL. B, Before extinction, rats were infused (arrow) with either the β-receptor antagonist propranolol (n = 9) or saline (n = 9). Rats infused with propranolol into IL showed normal within-session extinction, but were impaired in their recall of extinction on day 3. C, Infusion of propranolol immediately after extinction had no effect (propranolol, n = 5; saline, n = 5). Error bars indicate SEM.