Home-cage activity test v2 01/Nov/2008 RIKENMPP_006_002 test 0 1 testSt test modification

One indicator of behavioral abnormalities in animals is changes in activity (locomotor activity). Activity changes, however, vary significantly depending on the environment in which the measurements are made. Activity also is clearly influenced by circadian rhythms (sleep and alertness). When placed in a new and unfamiliar environment, animals are strongly affected by emotions, such as fear and anxiety. The activity of mice is analyzed using the home-cage activity test. To quantify home cage activity, the test requires apparatuses that are used exclusively for the test. Once the apparatuses are installed, however, the test can be performed easily and used to analyze a number of mice. Accurate measurement of circadian rhythms requires that the mice are kept in the dark for a long period of time, preventing many mice from being analyzed in a short period of time. This protocol describes the apparatuses necessary for the home-cage activity test under light/dark conditions as well as a relatively simple analytical method.

These procedures are applicable to the mouse phenotyping platform at the RIKEN BRC. Testing should be performed by trained staff members who understand the safety and hygiene rules required by RIKEN. Any queries, comments, or suggestions, relating either to this SOP in general or to a specific problem encountered during a procedure, should be addressed to the Behavioral Neuroscience Unit Leader. Any deviation from this protocol must be reported to the Behavioral Neuroscience Unit Leader.

Testing is performed in accordance with the specified safety and hygiene rules.

Various types of activity measurement instruments are available, such as an infrared-ray emission detector, a magnetic field change detector (Animex type), an infrared beam grid detector, and a video image analyzer. Because each of these instruments has its own set of advantages and drawbacks, it is advisable to purchase one that meets the research objectives and is compatible with existing research facilities. We use infrared-ray emission detectors, which employ passive sensors with no physical output, such as light emission, because the detectors are tolerant to environmental noise and data processing can be performed quickly with no high-level computer specifications. In addition, the detector combined with a device to measure water and food intake and a night-time video recorder results in a detailed data set.

To ensure the accuracy of the data, avoid entering and leaving the experimental room and unnecessary noise. The date and time of loud noises in or around the experimental room should be recorded as reference information for data analysis. Place experimental cages at adequate intervals and turn off the power for other instruments that may interfere with data collection.

Cage and cage top to measure activity. A hardware system for mouse activity measurements assembled from a detector of magnetic field changes, a data collection chamber, a data collection slave PC, and a data collection master PC (Neuroscience Co., Japan). Data collection and data analysis software (ABsystem 3.02; Neuroscience Co., Japan)

Wood chips for the rearing cage Water bottle Rearing food

Place mice individually in measuring cages for 24 hours to habituate the mouse to experimental environment. Food and water are available ad libitum. Start measurements using the method for each instrument. After the 1-day habituation period and a 5-day measuring period, complete the measurements using the method for each instrument. Remove the instruments and bring the mouse back to the usual rearing cage in the rearing room. Categorize the collected data for the various parameters to allow comparisons with control data. Extractable parameters depend on the measuring instrument and the analysis software. To assess changes in activity and the overall pattern of activity, observe plotted graphs that show the time course of activity. The units of the time axis depend on the objective of the analysis. Objective visual examination of different activity rhythms by a researcher, however, is limited. Therefore, it is necessary to perform period analysis using a chi-square periodogram, power spectrum, or least square spectrum.