Importance of touch for the blind mole rat (Spalax ehrenbergi) in learning a complex maze

We examined the involvement of the sense of touch in familiarization and learning of a maze. Each maze (110 × 120 cm) comprised one route leading to the target and six dead-end routes. Forty-eight mole rats were tested in a wide maze (9 × 9 cm; wider than their body circumference); 24 additional animals were tested in a narrow maze (5.5 × 5.5 cm; equaling their body circumference). Animals were run 5 times a day for 3 days. For each run, we measured the number of errors and length of time required to reach the target, where the mole rat received a food reward. The learning curve of the mole rats in both types of maze was exponential; after 8-10 runs the animals already demonstrated maximum performance. The mole rats in the wide maze took longer in the first run (p < 0.01) in comparison with those in the narrow maze. In the remaining trials no difference was found between the performances of the two groups. Differences occurred in the type of movement of the mole rats in the two mazes. During the trials, those in the wide maze made contact with two of its walls simultaneously, despite their body circumference being less than that of the maze tunnel. In order to do so, they maneuvered themselves so that every time they stopped, their chest and stomach maintained continuous contact with one of the walls, while their head was in contact with the opposite wall. Moreover, at T-junctions of the wide maze, the mole rats would stop and simultaneously make contact with three or even four of the walls. This behavior was observed mainly during the early trials and gradually diminished. These results indicate the importance of contact with the walls during the familiarity and learning phases of a new tunnel system. This unique behavioral pattern of the mole rat suggests that such contact serves the animal not only to sense and avoid obstacles, but also provides it with somatosensory information to facilitate spatial navigation.