Knowledge Base

Introduction

The Morris Water Maze Test

The Morris water maze is a behavioral procedure designed to test spatial memory. It was developed by neuroscientist Richard G. Morris in 1984, and since its initial description it has become a very popular paradigm for the study of learning and memory in rodents (D'Hooge and De Deyn, 2001).

In the water maze paradigm, a rat or mouse is placed into a small circular pool of water which contains a hidden platform (the Atlantis platform). The platform is either fixed (a few millimeters below the water surface) or adjustable. In the latter case, the platform is submerged at the start of the trial (about 15 centimeters, depending on the device) and remains submerged until the subject finds the location of the platform. The platform is then automatically raised. Visual cues, such as colored shapes, are placed around the pool to aid the animal in learning to locate the platform. After sufficient training, a capable rat can swim directly from any release point to the platform. Next, animals are treated and the effects on spatial learning and memory are evaluated based on how they now perform in the Morris water maze.

The Sample Experiment

EthoVision XT comes with a sample experiment that shows you how a Morris water maze test is carried out with EthoVision XT. It includes a number of videos from a true research project and shows interesting patterns of spatial behavior depending on the age of the subject.

If the sample experiment was installed during installation of EthoVision XT, you can open it directly: Choose File > Restore Backup and browse to C:\Users\Public\Documents\Noldus\EthoVision XT\Experiments\Sample Experiments. Select the file with extension EVZ and click Open.

If you do not find the sample experiment, download it from MyNoldus.com. First log in or register, then choose Downloads > EthoVision XT > Sample Experiments.

References

• D'Hooge, R. and De Deyn, P.P. (2001). Applications of the Morris water maze in the study of learning and memory. Brain Research Reviews, 60-90.
• Gallagher, M., Burwell, R. and Burchinal, M. (1993). Severity of spatial learning impairment in aging: development of a learning index for performance in the Morris water maze. Behavioral Neuroscience, 618-626.

For the complete list of publications, see the results in Google Scholar.

Physical Setup

The following suggestions are meant to optimize video tracking:

• The camera should have a good view of the entire region the animal can be in. The arena should fill the field of view.
• There must be maximum contrast between the background and the animal. If you use dark rats in the water maze, you can color the water with milk powder (400 g, pre-dissolved in 2 l). It is also possible to track white rats or mice with dark coloring in the water: add 300 g of tempera black nontoxic powdered paint to a 45-l pool.
• If you have reflections in your image, EthoVision XT may confuse those reflections with your subject, and track the reflections rather than your animal. Place four (or more) bulbs round the pool, below the level of the water surface or other indirect lighting above the water maze. 'Globe' type bulbs are ideal (twice the diameter as standard incandescent light bulbs). They should be close enough to the pool wall so that there is no direct line of sight between the bulbs and the camera lens. The light is reflected off the walls and ceiling, so that it only reaches both the lens and water surface indirectly.
• The water temperature should be ± 26 °C, which is cold enough to encourage the animals to seek the platform, but not too cold to induce hypothermia.

Source: EthoVision XT 18 - Application Manual, Noldus Information Technology