Novel object recognition is a test used for measuring memory in laboratory rodents. Subjects are typically tested over two trials, with a pre-test habituation phase. In the pre-test rodents are exposed to an empty arena to habituate to the new environment. During the first trial, the animal is allowed to freely explore the arena containing two identical objects. Researchers record the subject’s interaction time with the two objects. It is expected that animals will spend roughly equal time interacting with either object. During the second trial, which can be anywhere from an hour to 24-hours or more after the first trial, the animal is returned to the same arena with two objects — but this time one object is novel and the other is reused from the first trial. Rodents typically spend more time exploring a novel object, so those that show preference for the novel object versus the familiar object are presumed to have better memory of their experience during the first trial. Rodents that show no preference for either object may not recall having seen the first object already.
Environment: The testing room should be a quiet space with WiFi access. Depending on the objective of a particular experiment, testing can be performed during day or night and the room can be illuminated with dim white light or red light. The arena should be set up several feet from where the experimenter sits. For the first trial, add two identical objects to the arena. For the second trial, replace one of the objects with a novel object. Place objects in opposite corners of the arena, but remember to counterbalance them across trials.
Streaming: Log in to the BehaviorCloud Camera app and begin streaming. Mount the mobile device running the BehaviorCloud Camera app so the entire arena is in full view. It is important for the mobile device and the arena to remain in the same positions throughout testing. The position of the arena can be marked out on the floor in case of accidental bumping during the experiment.
Controls: A laptop or a second mobile device should be set up where the experimenter plans to sit during trials. Log in to app.behaviorcloud.com to reach the experiment dashboard and create a new experiment.
Preparation: Mice should be brought into the testing room approximately 30 minutes before testing to acclimate to the environment.
Calibration: To get an accurate measure of distance traveled by each rodent, it is important to calibrate the system at the beginning of an experiment. From the laptop or second mobile device, click calibration and place the checkerboard calibration pattern into the arena in full view. A preview window will show the system automatically recognize the pattern and calculate a distance measurement. Click the arrow to continue to the next step.
Starting a trial: Click Experiment Video and then the plus icon to add a new subject. Select the mobile device that is being used for streaming, enter the subject ID, and enter the duration of the test in seconds. On the next screen, you will be prompted to clear the arena, which means to remove any animals, people, or other moving objects from the view. Then you will be prompted to insert the subject and begin the trial.
Finishing a trial: When the scheduled duration has elapsed, the test will automatically end and you will be prompted to enter the next subject ID. Repeat running subjects until you are finished.
BehaviorCloud makes your raw video data and analysis tools accessible from anywhere using your online account. At your desk in the lab (or at your favorite coffee shop), log in to your account and run your analysis.
Setting the boundary: Set a tracking boundary to specify the area to be analyzed. Click save.
Generate position data: Next generate XY position data for all of the subjects.
Set zones: Draw and label zones to specify the area around each of the objects. Click save.
Generate data files: Generate zoned activity data for all of the subjects and download the .csv file to get the time spent exploring each object.
Calculate percent time spent exploring the novel object out of total time exploring either object for the first and second trial. During the first trial, it is expected that animals will spend roughly equal time exploring either object. During the second time, higher percent preference for the novel object indicates better recognition memory.
While you’re working on novel object recognition, don’t forget that BehaviorCloud makes it easy to invite collaborators to view or contribute to experiments. Just click the menu next to an experiment to manage sharing/collaborators. Happy testing!