Figure 9.

Reduced fear extinction recall in Tshz1 cKOs. A, On day 2, Tshz1 cKOs (n = 16) exhibited reduced exploratory behavior before stimulus exposure compared with controls (n = 14). Following paired CS-US exposure, both controls and mutants exhibited reduced movement. B, In a novel environment on day 4, Tshz1 cKOs exhibited reduced exploratory behavior before CS exposure. Both Tshz1 cKOs and controls showed reduced movement following CS exposure. C, On day 5, following the initial CS exposure, control mice activity rate was significantly elevated compared with the first CS exposure on day 4, indicative of an extinguished fear response. Tshz1 cKOs moved less than controls in response to the CS and did not exhibit a significantly different response than they did on day 4, suggesting impaired expression of fear extinction. Data are mean ± SEM. *p ≤ 0.05 (ANOVA). † p ≤ 0.05 (one-tailed paired t test).