Jeremy Davidson Bailoo ^1* Susan E. Bergeson ¹ Igor Ponomarev ² Joshua O Willms ² Brent R Kisby ² Gail A Cornwall ¹ Clinton C MacDonald ¹ John Josh Lawrence ^2,3 Vadivel Ganapathy ⁴ Sathish Sivaprakasam ¹ Praneetha Panthagani ² Scott Trasti ¹ Justin A Varholick ⁵ Michael Findlater ⁶ Amrika Deonarine ^7*

• ¹ Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States
• ² Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, Texas, United States
• ³ Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, Texas, United States
• ⁴ Texas Tech University Health Sciences Center, Lubbock, United States
• ⁵ Department of Biology, University of Florida, Gainesville, FL, United States
• ⁶ Department of Chemistry and Biochemistry, School of Natural Sciences, University of California, Merced, Merced, California, United States
• ⁷ Department of Civil, Environmental, & Construction Engineering, Edward E. Whitacre, Jr. College of Engineering, Texas Tech University, Lubbock, Texas, United States

The Morris Water Maze (MWM) is the most commonly used assay for evaluating learning and memory in laboratory mice. Despite its widespread use, contemporary reviews have highlighted substantial methodological variation in experimental protocols and that the associated testing procedures are acutely (each trial) and chronically (testing across days) stressful; stress impairs attention, memory consolidation and the retrieval of learned information. Moreover, the interpretation of behavior within the MWM is often difficult because of wall hugging, non-spatial swim strategies, floating, and jumping off the escape platform. Together, these issues may compromise the reproducibility, generalizability, and predictability of experimental results, as well as animal welfare. To address these issues, and as an initial proof-of-principle, we first narrowed the spatial dimensions of the MWM by using a T-insert, which constrained and reduced the overall length of time/distance that the animal must swim in order to navigate to the escape platform, thus reducing stress and off-task behavior. Given the robust performance observed across spatial acquisition (learning and memory) as well as during reversal learning (executive function), we further reduced (by 43%) the overall distance and time that the animal must swim in order to find the escape platform in a bespoke standalone Water T-Maze (WTM). We show, across five experiments, procedural refinements to our protocol and demonstrate robust, reliable and reproducible indicators of learning, memory and executive functioning in a task that is also significantly more efficient (3 days of testing within the WTM vs. 11 days of testing within the MWM). Taken together, our WTM apparatus and protocol are a significant improvement over other waterbased apparatuses and protocols for evaluating learning, memory, and executive functioning in laboratory mice.