The larger one was 16 cm high, with a cylindrical shape and the smaller one was 4 cm high, with a column shape . The objects was placed in the center of the OF test box . The number of contacts with the object weremeasured . Lrrtm1 KO mice contacted the large object significantly less frequently than didWTmice. This result was also supported by trace pattern abnormality . In contrast, when small objects were placed in the OF box, KO and WT mice contacted the object equally ; this was significantly different from the case with the large object =5.4, two-way ANOVA for genotype-object size interaction). To test whether the perception of ����novelty���� was altered in Lrrtm1 KO mice, we also used the small objects 3�C4 cm high cone, sphere, and cube in addition to the column . The surfaces of these objects were differentially labeled with black or gray on a white background. In a home cage , contact with the small objects by KO mice was significantly more frequent than by WT mice , indicating that the approach to inanimate objects was context dependent. In the novel object recognition test, two identical objects were first placed in the cage. After 15 min of exposure to the objects , one object was replaced with a new one that differed in terms of shape and surface pattern. In the following 15 min, the mice were exposed to both the new, unfamiliar object and the familiar object . The contacts with each object were counted in both sessions. In the NOR test session, both WT and Lrrtm1 KO mice showed significantly more frequent contact with the novel object than with the familiar one, and the novel object preference indices of the WT and KO mice were almost the same . The result suggested that an altered preference for ����novelty���� might not explain the above-described behavioral SP600125 customer reviews abnormalities. To examine responses to animate objects, we Mdm2 inhibitor performed a social discrimination test . In this test, the mice were first habituated to empty cages placed in two corners of the OF box. Before the first session, one empty cage was replaced with a cage containing a mouse. After the first session of 15 min, a new caged mouse and the familiar caged mouse were presented to the test mouse for 15 min as the second session. The results were quantified as the time spent near each cage and as the number of direct contacts through the wire slits. First, we noticed that Lrrtm1 KO mice avoided approaching the empty cages in the habituation session .