Figure 4.

Updating trace fear memory with a single trial of delay changes the neural circuit so that the amygdala is now required for extinction. (a) The experimental timeline. (b) Freezing during each period (Baseline, BL; CS presentation, CS; trace interval, TI, post-CS, post) of the update session. (c) Freezing during the first 8 CS presentations of the extinction session. (d) Freezing during the CS test. Intra-amygdala APV impaired extinction for animals given the shifted delay update but had no effect on animals given the non-shifted trace update. Data are presented as mean±SEM **p<0.01; n=6–8/group. ACSF, artificial cerebrospinal fluid (vehicle); AMY, amygdala; APV, aminophosphonovaleric acid (NMDAR antagonist); BL, baseline; CS, conditional stimulus.