vHPC is necessary for both fear expression and extinction memory. (a) Cannula placements in vHPC. (b) Inactivation of vHPC (MUS: n=14; SAL: n=14) prior to extinction training (Day 2) reduced conditioned freezing during trial blocks 1–7 and 10. *p<0.05, Tukey's post hoc. During extinction retrieval (Day 3), MUS-infused rats displayed significantly higher levels of freezing during trial blocks 2–4. *p<0.05, Tukey's post hoc. (b, inset) Effects on suppression were similar to conditioned freezing. Inactivation reduced suppression on trial block 1 during extinction training (Day 2). *p<0.05, Student's t-test. During extinction retrieval (Day 3), MUS-infused rats displayed significantly higher levels of suppression during the first trial block. *p<0.05, Student's t-test. Data are represented as group averages.