Novel Object Recognition Memory

Male and female F1 rats were handled for 2 minutes per day for a minimum of 5 days preceding the onset of behavioral procedures. All experiments were at lights off and in the same testing environment described above but with no spatial cues inside of the arenas. During habituation, animals were placed into the testing environment without objects present for 10 minutes per day, for 5 days. 24 hours after the last habituation session, animals were returned to the chamber, which now contained two identical objects, for 10 minutes. Testing took place 24 hours after the training session. One of the training objects was removed, and a novel object was placed in the same position. Training and testing sessions were recorded and time spent exploring the objects was scored by a trained observer blind to siring conditions. Exploration of objects was defined as actively sniffing or otherwise interacting with the objects, with the nose of the animals within 1 cm of the object. Preference index was calculated as follows: (time exploring novel object/total time exploring both objects) × 100.