Novel object recognition test
The NORT is used to evaluate declarative memory and object recognition and has an essential application in the study of cognitive alterations. The test was performed in a Plexiglas box (40 cm×40 cm×65 cm) and the task procedures consist of three phases: habituation, training, and test. The rats were habituated to the test box for 20 min on the habituation phase (24 h before the training phase). During the training phase, two identical objects were placed in opposite walls of the testing box, and the animals were allowed to explore for 10 min. Then, we changed one object to a different shape and color in the test phase, and a test session of 10 min was performed after a retention interval of either 2 h. The behavior of the subjects in each trial was recorded on video, and the exploration time was scored by an observer blinded to the experimental conditions. Exploration was defined as sniffing, biting, licking or touching the object with the nose. Turning around or sitting on the object was not considered exploratory behavior. During the test session, a discrimination index (DI) was calculated using the formula (B−A)/(B+A), with B being the time spent exploring the novel object and A being the time spent exploring the familiar object.