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The Morris water maze is a spatial navigation task. Dating back to the early 1900’s, a variety of experimental procedures have been developed for animals that have the escape from water as a means to motivate learning and memory processes. Water maze tasks primarily designed to measure spatial learning and the recall of previously learned information have become quite useful for evaluating the effects of aging, experimental lesions, and drug effects, especially in rodents. A literature search in July of 2006 on Science Direct dating back to 1996 yielded 1,240 scientific research articles when using the search works “Morris water maze”. This task has earned the distinction as a must-have in any rodent behavioral laboratory.
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While this may seem like a very simple task it actually is quite challenging to the rodent and requires some rather sophisticated behaviors. Initially the rat must discover the spatial location of relevant visual cues pertaining to the location of the hidden platform. This information is processed, consolidated, and stored. During subsequent testing this information must be retrieved. If this is all done correctly it is reflected in a decreased latency to reach the hidden platform with successive testing.
The general processes utilized in the rodent for visuospatial navigation also contribute to normal everyday cognitive processing in humans. Although there is an obvious difference in sophistication when comparing human and rodent cognitive abilities, this task is highly practical as a measure of memory in regards to visual and spatial navigation (adapted from Terry 2001).
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In a very simple version of this task, a large pool of water (maintained at room temperature) contains a fixed platform hidden just below the surface of the water. The platform is invisible to the rodents that participate in these experiments. Rats are tested individually by placing the subject in one of four quadrants. The time and/or distance traveled to reach the platform is recorded by the experimenter. Using visual cues in the testing room, rats become progressively more efficient at locating the hidden platform (reflected in shorter time and/or distance traveled), with each subsequent exposure to the water maze.
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