Altered social interaction pattern of Sept4Tg/+mice. (A) Schematic diagrams of the three-chamber sociability and social novelty preference tests . (Left) The sociability test setup. Each mouse was scored for the time spent in the middle habituated chamber (M), the left chamber containing an unfamiliar C57BL/6J mouse (Stranger 1, S1) in a wire cage, or the right chamber with an empty wire cage (E). (Right) The social novelty preference test following the sociability test uses the same apparatus, except for a novel unfamiliar C57BL/6J mouse (Stranger 2, S2) caged in the right chamber in addition to the now-familiar C57BL/6J mouse (Stranger 1, S1) remaining in the left cage/chamber. (B, D) There was no difference in the sociability indices (S1 over E) between the genotypes. [(B) F1,32 = 1.68, p = 0.20, (D) F1,32 = 4.75, p = 0. 037]. (C, E) In the social novelty preference test (Step2) after the sociability test (Step1), Sept4Tg/+ mice exhibited significantly less preference for S2 over S1 than Sept4+/+ mice, indicative of their reduced curiosity in the novel social stimuli and/or augmented persistence to the familiar social stimuli (n = 20, 14). [(C) F1,32 = 3.06, p = 0.09, (E) F1,32 = 4.69, p = 0. 038].