Knockout of the CatB gene, but not BACE1, in AβPPWT/Lon mice improves memory retention. The day after the last training session, the submerged platform was removed and the mice were allowed to swim in the pool for 60 s. The percent time each animal swam in the quadrant from which the platform had been removed (Northeast (NE) quadrant, (Panel A) and the percent time an animal swam in the annulus of the pool were recorded (Panel B). Greater memory retention is reflected in a higher percent time in the NE quadrant and lower percent time in the annulus. AβPPWT/Lon (control), AβPPWT/Lon × CatB KO (CatB KO), and AβPPWT/Lon × BACE1 KO (BACE1 KO) mice had percent times in the quadrant of 10%, 33%, and 11% (Panel A) and in the annulus of 42%, 17%, and 39% (Panel B). Values are expressed as the mean ± s.e.m., and n = 10 per group. ***Statistically significant with p < 0.05.