Hypoactivity and increased anxiety-related behavior in a novel environment and reduced social interactions in the home cages of 1d2d-PSD-95-EGFP KI mice. A–D, Light/dark transition test (WT controls, open bars, n = 15; KI, filled bars, n = 16): distance traveled in the light/dark compartments (A), time spent in the light compartment (B), number of light/dark transitions (C), and latency to enter the light compartment (D) were recorded. E–H, Open field test (WT controls, open circles, n = 16; KI, filled circles, n = 16): total distance traveled (E), vertical activity (F), time spent in the center of the compartment (G), and stereotypic counts (H) were recorded. I–J, Elevated plus maze test (WT controls, open bars, n = 15; KI, filled bars, n = 13): distance traveled in the arms (I), number of entries into the arms (J), number of entries into the open arms (K), and time spent in the open arms (L) were recorded. M–N, Social interaction test in the home cages (WT controls, open circles, n = 7; KI, filled circles, n = 6): KI mice were more active at night than WT mice (M) and the mean number of particles representing the mice acting separately were significantly higher all day long in the KI mice compared to the WT mice (N).