Fig. 4.
Mek inhibitors impair contextual fear extinction. (A) U0126 injected i.h. immediately after individual extinction trials prevented extinction as indicated by significantly higher freezing of U0126-injected mice when compared to their vehicle controls (p < 0.001). (B) PD9859 injected in the same fashion also impaired extinction (p < 0.001). (C) Injection of U0126 3 into the adjacent somatosensory cortex did not affect extinction when compared to the vehicle-injected control. (D) Similarly, PD9859 was ineffective after i.c. injection. No. of mice/group was 10–15. Statistically significant differences were revealed by one-way ANOVA followed by Scheffés test : *p < 0.01, **p < 0.001 vs vehicle control.