Spatial learning and memory in the blind mole-rat in comparison with the laboratory rat and Levant vole

Studies dealing with spatial orientation in mammals have mostly dealt with surface-dwelling species. We studied the ability of a subterranean rodent to orient in space and compared it with two species of rodents that spend most of their lives above ground. The solitary blind mole-rat, Spalax ehrenbergi, inhabits an extensive, branching tunnel system that it digs itself and in which it spends its entire life. We examined its ability to learn and remember a winding path towards a goal in a multiple labyrinth and compared it with Levant voles, Microtus guentheri, and laboratory rats, Rattus norvegicus. The mole-rats learned significantly faster than the rats and voles. Furthermore, their ability to remember the maze was significantly better than that of the rats after 2, 7, 30 and 60 days from the end of the learning experiment and significantly better than the voles after 120 days. The mole-rats still retained ca. 45% of their optimal performance at the end of the learning experiment after 4 months compared with 20% for the voles after 4 months and less than 20% for the rats after 2 months. Despite having lost its vision, the mole-rat was thus more able to orient in a complex maze than the surface-dwelling vole and laboratory rat. We suggest that the mole-rat compensates for the sensory limitations imposed by the subterranean niche and for its loss of vision by relying on the Earth's magnetic field and internal cues to steer its course efficiently. We discuss the possible mechanisms of orientation.