Increased exploratory rearing in Kv4.2 knockout (KO) mice. (A) KO mice showed more rearing behavior than wild-type (WT) controls in a novel empty-cage environment. (B) Genotypes did not differ in nociception as measured by the hot-plate tes, or in (C) the acoustic startle response (D) or prepulse inhibition of startle. (E) Light and dark phase home-cage activity was similar between genotypes. Data are mean ± SEM; n = 8-10/genotype. *P < 0.05; **P < 0.01.