Search strategy assignments during Morris water maze testing. Search strategies were assigned for each mouse during the acquisition phase. Search strategies were categorized into three main groups: Spatial, Non-spatial Systematic, and Peripheral Looping. The data (right panel) show a disturbance in the formation of spatial memory in the p50−/− mice as represented by fluctuations in their usage of spatial search strategies. p50+/+ mice, on the other hand (left panel) show an expected gradual and steady increase in the proficient use of this hippocampal-dependent spatial strategy over time, which is consistent with several other studies. Chi-square tests showed several significant associations (P < 0.05) between strain and the adopted search strategies (days 2, 3, 4, and 7).