G4-DNA is required for both fear extinction and fear acquisition. A, Timeline of training and (B) within-session extinction training. There was no significant difference between groups. C, Visual representation of infusion of virus into infralimbic PFC with some viral spread outside of target zone. D, These infusions did not lead to a significant impairment in memory for fear extinction following a 60 CS training protocol in Context B as both groups showed a significant reduction in comparison with RC SC (n = 8/group, one-way ANOVA F_(3,39) = 4.466, *p < 0.01, Sidak post hoc test; RC scrambled shRNA vs EXT scrambled shRNA, **p = 0.0034; Holm–Sidak; RC SC shRNA vs EXT DHX36 shRNA, **p = 0.0034; EXT, extinction trained; RC, retention control; Avg CS, average of 3 CS exposures). E, DHX36 shRNA did lead to a significant impairment in expression of extinction memory in Context A following a 60 CS training protocol in Context B (n = 8/group, two-way ANOVA F_(3,39) = 5.0390, *p < 0.05, Sidak post hoc test; RC scrambled shRNA vs EXT scrambled shRNA, **p = 0.01; EXT scrambled shRNA vs EXT DHX36 shRNA, *p = 0.0492). F, Timeline of training and infusion (G) of DHX36 shRNA into the prelimbic PFC. This led to a significant impairment in acquisition (n = 8/group, two-way ANOVA, F_(3,56) = 4.335, p < 0.0001, Sidak post hoc test; FC Scrambled vs FC DHX36, CS2, **p = 0.0056; CS3, ****p < 0.0001). H, However, there was no significant difference between the two groups at the test in Context A.