Novel object recognition test

The novel object recognition (NOR) test was used to assess learning and memory in mice, as it mimics the learning and memory processes of human behavior [47]. The test is based on the spontaneous interest displayed by mice in exploring a new object, rather than a familiar one. The test had 3 phases: in the habituation phase, each mouse was allowed to roam freely on an open-field area (an empty black box 60 cm wide × 60 cm deep × 60 cm high) for 10 min; in the familiarization phase, 2 identical red wood cylinders (A1 and A2) were presented for 10 min; after 24 h, one of these cylinders was replaced by a novel object, a same-sized plastic green cylinder (B), after which recognition memory (the time spent exploring each object) was recorded.The discrimination index (DI) was calculated as (N-F) /(N+F) × 100%, where N = time spent exploring the novel object (green cylinder), and F = time spent exploring the familiar object (red cylinder).