Fig. 9.

Fear extinction is marginally improved by rescue of the CB1 receptor specifically in forebrain GABAergic neurons. Animals were fear conditioned on day 0 and re-exposed to the tone (CS) for 200 s during extinction sessions on day 1 (d1), d2, d3 and d10 after conditioning. As baseline immobility before the tone differed between groups (see Fig. S4b), subsequent measures of fear extinction were adjusted for baseline immobility using the subtraction method. a Immobility to the tone, expressed per 20-s time bin, showed no significant three-way interaction between days, bins, and groups, but a significant effect of group. Post hoc comparisons revealed that Stop-CB1 animals had higher levels of immobility than CB1-RS mice, with intermediate levels in GABA-CB1-RS mice. b Within-session fear extinction is expressed as the reduction in immobility between the first and the last 20 s of the 200-s CS presentation, normalized to the initial response (as shown in Fig. S4c) and was significantly stronger in CB1-RS mice than in mice of both other groups. Data are presented as mean ± SEM; animal numbers are indicated; *P < 0.05; **P < 0.01 in repeated measures ANOVA followed by Tukey multiple comparison test; details of statistical analysis in supplementary Table S2