The radial arm maze consists of an array of arms, usually eight or more, which radiate from a central starting point. At the end of each arm is a cup that may or may not contain a food reward. The design ensures that, after checking for food at the end of each arm, the animal is always forced to return to the central platform before making another choice. As a result, the animal always has eight possible options.
Animals are trained to recognize that only one of the arms will contain food. Investigators measure the amount of time it takes for animals to find the arm leading to food, as well as the number of times it traverses an arm it has previously visited. Exploring a previously visited arm indicates that the animal did not remember previously choosing that spatial path. This is a relatively difficult task for rodents, requiring several days or weeks to train rats and many weeks to train mice.
- The radial maze is made of white lusterless Perspex (each arm, 50 cm long × 10 cm wide × 40 cm tall), placed in a dimly lit room (50 lx), with room temperature maintained at 23 ± 1 C°.
- The maze itself has no landmarks; the only landmarks are outside the radial maze on the surrounding walls.
- During four consecutive days, food treat (2 g) is scattered in home cages to avoid neophobia. Mice are familiarized with the maze for 3 d before training: on the first day, mice are placed in the maze for 20 min with scattered food reward (60 mg food treat).
- On the second and third days, mice are placed in the maze for 15 min and are able to consume the reward only from the food cups at the ends of the arms (15 mg in each arm).
- During the trial period, food is deprived for 16 h before each experimental session. Trial begins as the mouse is placed in the central arena within an opaque cylinder that is removed at the beginning of each trial. In the learning phase, mice are given daily training trial over a period of 7 to 8 d and expected to learn to visit baited arms (not adjacent arms).
- Trial ends when one of the following conditions is reached:
a) all four baited arms have been visited or
b) the trial lasted for more than 10 min .