study of fear and anxiety
The elevated plus-maze (EPM) is a most popular, behavioral test used in the study of fear and anxiety. In the case of mice and rats, freezing behavior and avoidance of brightly lit areas are used as measures to assess anxiety and fear in behavioral tests such as the open field test. The EPM is based on the conflict between the natural tendency of mice and rats. Animals are provided the opportunity to explore a novel environment consisting of an elevated maze with two intersecting arms; a “closed” arm with tall walls creating an alley that intersects with an ‘open’ arm without walls that presents an unprotected walking surface . The EPM is commonly used by the pharmaceutical industry . Mazes can be constructed of a range of materials, including wood, clear or colored Plexiglas. The size of the maze varies by species, laboratory, and manufacturer.
The subject is given a free choice, during the trial, to choose either one of the baited arms unlike in the Rewarded Alternation task where one of the arms is blocked. Once the subject has made its choice, it is confined to that goal arm by closing the respective door for 30 seconds. The subject is removed from the goal arm after it has consumed the food reward and the doors in the maze are opened. The subject is then once again placed in the start arm and is expected to alternate its choice from its previous selection. If the subject visits the unvisited arm, it is allowed to consume the food reward or else, in case it visits the already visited arm it is allowed to see that the food well is empty before it is removed from the maze.
Each trial lasts no longer than 2 minutes, and the procedure is repeated for each of the animals on a ten trial per day basis for up to twelve testing days.
Since behavioral testing apparatuses are often difficult or impossible to disassemble and thoroughly disinfect due to their complexity.