I am doing a baseline + 2 rounds of behavioural testing (NOR + NLR) - so total 3 rounds of testing, all 1 week apart in male SD rats. Is it necessary to habituate them before every test, or is habituating them once prior to baseline testing sufficient?
Also, do rats get bored if they perform too many tests in a short period of time? If so, how do you overcome this?
Dear Shi Li , when you perform NOR or NLR for the first time, you should use a 3-session protocol: 1) habituation to the arena (without objects); training (with objects); 3) test (with objects). The habituation session with the empty arena has the aim of reducing stress in response to a novel environment, which can lead some mice to high thigmotaxis (high percentage of time spent walking close to the walls) and scarce exploration of the objects.
If you need to repeat NOR or NLR other 2 times with an interval of 1 week, no habituation session is required. You can perform directly the training and test sessions. The habituation session is needed only when animals are exposed for the first time to a new arena.
Regarding your second question, yes, unfortunately mice and rats lose interest in exploring the objects if NOR/NLR is repeated too many times over a short period of time. You can check this similar question for further information:
https://www.researchgate.net/post/The_Novel_Object_Recognition_Test_NORT_Frequency_and_effectiveness
Shi Li, it is correct that rodents lose interest in repeated experiments in a short time. I have done this several times for a very extensive and expensive study. First, the time they explore anything goes rapidly down. In my opinion, with good sets of tested objects, you can do a few rounds.
Dear Shi Li If you are testing the rats on a skillful task such as reaching and grasping, it is wiser to allow them to be in the testing chamber or arena for few minutes before you conduct the data collection. If the task is as stereotypical as walking overground, you may get away with habituating them once in the starting of the study.
Yes, rats do get bored if engaged in a same task for longer period, especially if the task is award based and they are failing again and again in getting the reward. They will just stop performing and shun themselves. In our lab, we give a break of few minutes after waiting them to perform for max 10 minutes and put the rats back in their cage. They generally perform second testing.
Hope that helped.
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