The olfactory tubing maze: a new apparatus for studying learning and memory processes in mice.

In order to have an ethologically relevant behavioral task, we developed the olfactory tubing maze to study learning and memory processes in mice. Mice have to make two olfactory-reward associations across three training sessions. The maze is made up of four identical testing chambers connected to each other by semicircular cylinders. After having chosen one of two odors presented on each side of a testing chamber, the mice have to run to the next testing chamber. From one testing chamber to the next, the side for presentating each odor is randomly assigned. The mouse must run through the entire circular maze to make a response at the four testing chambers. A complete session consists of 20 trials made by running five times clockwise through the maze with 4 trials per run. The training and data recording are fully automated by a custom-made software program. Three different experiments were performed. The results indicated that mice can easily make the olfactory discriminative associations in this new apparatus. Analysis of the data suggests that it would be possible using this olfactory tubing maze to study sub-categories of memory similar in some respects to those observed in humans. Consequently, possible effects on learning and memory of classical treatments (i.e. pharmacological or lesions) or genetic modifications in transgenic or gene-targeting mice could be tested.