Automated radial 8-arm maze: A voluntary and stress-free behavior test to assess spatial learning and memory in mice.

The radial arm maze (RAM) is a common behavioral test to assess spatial working and reference memory in mice. However, conventional RAM experiments require a substantial degree of manual handling and animals are usually subjected to prolonged periods of food or water deprivation to achieve sufficient learning motivation resulting in stress-induced confounding effects and unwanted intra- and inter-subject variation. In a proof-of-concept approach to improve reliability and repeatability of results by refining the conventional maze methodology, we developed a voluntary, fully automated 8-arm RAM and tested its feasibility and usability using both spatial working and combined working/reference memory paradigms in ten female C57BL/6J mice. We demonstrate that experimental procedures of up to 7 days duration could be conducted without any manual animal handling and that mice up to 18 months of age showed robust spatial learning performance without any food or water restrictions being applied. Therefore, a voluntary, automated 8-arm RAM can serve to minimize variation in experimental results by reducing an animal's distress, suffering, and pain, which, in turn, contributes to the comprehensive application of 3R principles.