Fig. 7.

Impaired fear extinction of Gad1 KO rats in the fear‐conditioning test specialized for contextual memory (CTX experiment). (A) The time series of freezing behavior during conditioning on day 1 (WT, n = 8; KO, n = 8). The arrows indicate the timing of the electric shocks. (B) Although the baseline freezing (0–180 s) was not significantly different between two genotypes, shock‐induced freezing (210–700 s) in KO rats was lower compared with WT rats on day 1. (C) Total freezing behavior during the 10‐min contextual test on day 2. KO rats and WT rats displayed similar freezing in this protocol. (D) The freezing behavior of WT rats decreased with repetitive contextual tests, while that of KO rats remains unaltered. The results are presented as the average ± SEM. Data were analyzed using t‐test (B, C) or two‐way ANOVA (D). ^† P < 0.1, *P < 0.05, **P < 0.01., ***P < 0.001; NS, not significant. WT, wild‐type; KO, knockout.