Basal learning, locomotor activity, and pain sensitivity are normal in CRH KO mice. (A) Food-reinforced operant task as a measure of learning ability. CRH KO mice learn the task within the same time as WT animals (55.6 vs. 54 h at 100% acquisition, WT vs. KO). At acquisition (A, acquisition), responses/min are not different between WT and KO mice. At extinction (A, extinction) responses/min are again not different between WT and KO mice. (B) Open field. CRH KO mice have normal activity in an open field by ambulatory photocell counts. The total distance traveled was also similar between WT and KO mice (13,243 ± 2,145 vs. 13,484 ± 1,346 cm, WT vs. KO). (C) Pain sensitivity is normal in CRH KO mice, measured in both tail flick and hot plate assays. In A–C, WT, closed symbols; CRH KO, open symbols. Error bars indicate SEM.