Mouse Short- and Long-term Locomotor Activity Analyzed by Video Tracking Software

Summary

Locomotor activity (LMA) is a simple and easily performed measurement of behavior in mice. Coupling of video tracking software (VTS) and LMA allows for the improvement of specificity and sensitivity, especially when compared with the manual, line crossing method of LMA analysis. Additionally VTS allows long-term tracking of mouse LMA.

Abstract

Locomotor activity (LMA) is a simple and easily performed measurement of behavior in mice and other rodents. Improvements in video tracking software (VTS) have allowed it to be coupled to LMA testing, dramatically improving specificity and sensitivity when compared to the line crossings method with manual scoring. In addition, VTS enables high-throughput experimentation. While similar to automated video tracking used for the open field test (OFT), LMA testing is unique in that it allows mice to remain in their home cage and does not utilize the anxiogenic stimulus of bright lighting during the active phase of the light-dark cycle. Traditionally, LMA has been used for short periods of time (mins), while longer movement studies (hrs-days) have often used implanted transmitters and biotelemetry. With the option of real-time tracking, long-, like short-term LMA testing, can now be conducted using videography. Long-term LMA testing requires a specialized, but easily constructed, cage so that food and water (which is usually positioned on the cage top) does not obstruct videography. Importantly, videography and VTS allows for the quantification of parameters, such as path of mouse movement, that are difficult or unfeasible to measure with line crossing and/or biotelemetry. In sum, LMA testing coupled to VTS affords a more complete description of mouse movement and the ability to examine locomotion over an extended period of time.

Protocol

1. Short-term LMA Set Up and Procedure

1. Short-term LMA cage set up
   1. Test short-term LMA within the home cage of a single-housed mouse. To facilitate VTS-dependent image analysis, use bedding in high contrast with mouse color (i.e. dark colored bedding for white mice and light colored bedding for black mice).
   2. During short-term LMA testing, cover cages with clear ¼ in Plexiglas with 11 x ¼ in diameter holes to support appropriate ventilation.
2. Short-term LMA testing room
   1. Test mice in a clean environment in which they have been acclimated to for at....

Results

An example of results from a repeated measures, short-term LMA test is shown in Figure 1. This figure shows that after lipopolysaccharide (LPS) administration, mice housed in individually ventilated caging (IVC) recover short-term locomotor activity faster than mice housed in ambient environment caging (AEC) ⁶. While the initial loss of locomotor activity is similar between LPS injected groups, the recovery to basal LMA is more rapid in IVC-housed mice as was velocity of movement (Figu.......

Discussion

Symptoms of sickness in mice include lethargy, loss of interest in social and environmental surroundings, malaise and anorexia ^2-3. In mice and other rodents, LMA can be used to evaluate sickness after immune activation ^4-5. Additionally, long-term LMA offers the ability to track movement over a 24 hr (or greater) period, allowing analysis of treatment-induced alterations in circadian behavior or disturbances in sleep/wake patterns. LMA offers several advantages over other tests for sickness since i.......

Materials

Name	Company	Catalog Number	Comments
Name of Reagent/Material	Company	Catalog Number	Comments
Video camera	Sony	HDR-XR500V	Other, similar video cameras may work as well. The file storage format (codec/container) must be compatible with the VTS used. It is recommended when initially establishing a VTS to choose the VTS first and work with the vendor in choosing an appropriate camera, especially with respects to file format and video resolution compatibility.
Opaque cage dividers			Custom fabricated based on specific cage dimensions. To facilitate image analysis, dividers should be of a similar color to the cage bedding. Structurally fixed dividers are preferrable because they speed setup between multi-mice experiments, such as those involving repeated measurements. Sturdy transportable cage dividers can be constructed of 1/2 inch opaque plastic and joined via a series of cross laps.
Light or Dark bedding (opposite of mouse coat color)			Available from several laboratory animal supply distributors, depending on location.
Clear Plexiglas cage tops			Custom fabricated based on cage dimensions.
Automated video tracking software (EthoVision XT 7)	Noldus Information Technology		A variety of VTS manufacturers exist, use of other software may suffice.
PC	Dell Inc.		See VTS software providers minimum PC .requirements
White noise generator	Dohm	DS	A variety of white noise generators are available, depending on need.
Brooder clamp lights with red light bulbs			Several sizes and styles available. Number required depends on room size/lighting needs. Do not exceed 125 lumens in the testing room.
Lab bench or butcher paper			Paper should match or be very similar in color to the cage bedding.