Novel Object Recognition Test for Rodents

NORT was performed to evaluate short-term memory retention. It was done by a slight modification of previously published literature [51 (link)]. For habituation, each mouse was placed in a wooden box without any object for 10 min, 24 h before the test. On the testing day, mouse was placed in that same box containing two identical green round blocks for 5 min for the familiarization phase. After a 30 min interval, during the test phase one of the objects was replaced with an orange rectangular shaped object. The time spent by the mice exploring each object was recorded by video capture and analyzed. The results are presented as the discrimination index which is calculated by: (time exploring the novel object—time exploring the familiar object)/(time exploring the novel object + time exploring the familiar object). It is common rodent behavior for a mouse to explore a novel object over a familiar one. The premise for this test is that a mouse with a cognitive deficit will not be able to remember the old object during the test phase, therefore will spend a similar amount of time exploring each object. All experiments were performed between 10 a.m. and 12 p.m.