Spatial learning in Long-Evans Hooded rats and C57BL/6J mice: different strategies for different performance.

Spatial learning abilities of rodents have been extensively used to explore the management of a wide range of cognitive and emotional processes such as learning, memory, attention and anxiety. Knowledge about the organization and processing of spatial learning has mainly been obtained in rats. Due to increasing generation of genetically modified mice, cognitive abilities of mice are now extensively tested. The present paper aimed at comparing spatial representation, learning and strategies in C57BL/6J mice and Long-Evans Hooded rats when subjected to the same spatial learning paradigm, i.e. learning a food location in a crossmaze. We also analyzed the influence of environmental richness on learning modalities in both species. Our results showed that rats and mice could exhibit similar spatial learning abilities in some circumstances. However, Long-Evans rats and C57BL/6J mice may set up different strategies depending on the availability of visual information within the environment. Rats' learning strategies mainly relied on distant visual cues and seemed more efficient than those used by mice as they needed less time than mice to solve the task. We emphasize that the strategies of mice are less robust and flexible than the ones set up by rats. Finally, the richness of the environment was shown to affect speed and quality of spatial learning in both species.