Increased open-field locomotor activity and test-specific decreases in anxiety-like behavior in Kv4.2 knockout (KO) mice. KO mice traveled farther than wild-type (WT) controls in a novel open-field test, as shown via (A) a time-course analysis) and (B) over the full session. (C) Time spent in the center of the open field did not differ between genotypes. In the light/dark exploration test, genotypes did not differ in (D) percentage time spent in the lighted compartment, (E) entries into the lighted compartment or (F) distance traveled throughout the apparatus. In the elevated plus maze, KO mice spent a greater percentage of the session (G) in the open arms and made more entries into (H) the open arms, but not into (I) the closed arms, compared with wild-type (WT) controls. Data are mean ± SEM; n = 8-12/genotype. *P < 0.05; **P < 0.01.