Fig. 1

Increased novelty-induced hyperactivity in Scn2a^KO/+ mice. a In the open field task, the traveled distance was significantly increased in Scn2a^KO/+ (KO/+) mice in the second and third blocks of 10 min of the test (genotype-time interaction: F_2,40 = 3.137, p < 0.05). b Scn2a^KO/+ (KO/+) mice spent significantly more time in the center area than their WT (+/+) littermates (genotype-time interaction: F_2,40 = 3.806, NS; time effect: F_2,58 = 8.252, p < 0.001; genotype effect: F_1,29 = 18.01, p < 0.001). c The number of rearing events was also significantly increased in the Scn2a^KO/+ group (genotype-time interaction: F_2,40 = 2.646, NS; time effect: F_2,58 = 38.50, p < 0.001; genotype effect: F_1,29 = 36.85, p < 0.001). In the elevated-plus maze task, Scn2a^KO/+ mice also showed significant signs of hyperactivity, traveling longer distances (d) and visiting the different arms more often (e) than their WT littermates. The number of visits to the open arms (f) and the time spent in the open arms (g) were significantly increased in the Scn2a^KO/+ mice, and whereas WT mice showed a significant preference for the closed arms over the open ones (h) this was not the case for Scn2a^KO/+ animals. In the light-dark transition task, the latency to first enter the bright side (i) and the total number of side transitions (j) were not significantly different between Scn2a^KO/+ and WT mice, but Scn2a^KO/+ animals spent significantly less time on the bright side (k). OA open arm, C center, CA closed arm. Open field: WT: N = 24, Scn2a^KO/+: N = 30; elevated-plus maze: WT: N = 24, Scn2a^KO/+: N = 29; light-dark box: WT: N = 11, Scn2a^KO/+: N = 14. Values are expressed as mean ± standard error of the mean. Statistical significance was assessed using two-way repeated measures ANOVA followed by Sidak’s multiple comparison post-hoc test (a–c), one-way ANOVA (h, tested separately for WT and Scn2a^KO/+mice), or Student t test (d–g and i–k) with significance set at *p < 0.05, **p < 0.01 and ***p < 0.001