Attenuation of the initial exploratory activity of Sept4Tg/+mice in a novel environment. (A, B) The total distance traveled during the entire session of 120 min (A, 5-min step) and an expansion of the initial 5 min (B, 1-min step) in the open field test. In the initial 5 min (bar in A), the exploratory locomotive activity of Sept4Tg/+ mice was significantly less than that of Sept4+/+ mice (*, p = 0.032, n = 20, 14). The test was conducted at the age of 6 months (cf. Figure 4). [(A) F1,32 = 0.09, p = 0.77, genotype × time interaction, F23,736 = 1.14, p = 0.29, (B) F1,32 = 5.04, p = 0.032, genotype × time interaction, F4,128 = 2.86, p = 0.026.] (C, D) The center time during the entire session (C, 5-min step) and an expansion of 14–18 min (D, 1-min step) of the open field test. The center time, another index of the exploratory activity, tended to be reduced in Sept4Tg/+ mice, which was statistically significant during an early time frame (**, p = 0.004). [(C) F1,32 = 0.45, p = 0.51, genotype × time interaction, F23,736 = 0.63, p = 0.91, (D) F1,32 = 9.37, p = 0.004, genotype × time interaction, F4,128 = 0.39, p = 0.82].