Radial Water Tread (RWT) Maze


The natural tendency for mice to avoid bright light exposure is the basis for The Barnes Maze behavioral test.  Mice also abhor swimming which is the basis for the classic Morris Water Maze cognitive memory task.  The goal of the Radial Water Tread Maze is to pair the aversive qualities of both tasks in a paradigm that minimizes interpretive difficulties.  In this new task, the mice are introduced to a 30 inch galvanized, circular tub with nine holes cut in the side at regular intervals.  Eight of the holes are decoys which lead to dead ends.  One of the holes leads to a dark, escape “safe box” hosting a comforting heating pad.   All holes extend outward similar distances before either terminating, or bending at a 90 degree angle to prevent direct visual determination of the actual escape route.  To provide the escape incentives of the Barnes and Morris Mazes, the tub is filled with ~ 1 inch of water and a bright light is positioned directly over the entire apparatus.

A mouse is introduced to the center of the maze containing unique visual images and objects along its side functioning as spatial cues for the animal.  The mouse is then required to find the escape route from the enclosure.  Three metrics are used in this task: latency to escape, number of errors, and distance traveled to reach the escape hole.  Once the animal finds the escape route, it is allowed to remain in the heated safe box for one minute prior to engaging the next training trail.  An animal is given three trails per training day, and the testing period can be run across successive days to test long term memory acquisition.

A typical experiment employs a four-day training period before a test on the fifth day.  The animal is allowed to search for the correct escape hole for a 3 minute period, after which the animal is guided gently to the correct escape route by hand.

A long-term memory test conducted one, to several weeks, after the initial training period.

The length of the training period may extend past four days.

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