When we performed a probe test 24 h after the last training trial, the Fe-treated APP/PS1 mice showed no preference toward the target quadrant, indicating significant memory impairment, whereas the M-30 or NS398-treated APP/PS1 mice performed as well as the WT C57BL/6 mice (Figs. 8B-E). This evidence concerns the gene PSEN1 and memory impairment.