FIGURE 7.

Impaired spatial memory in the Morris water maze. (A) Mean escape latencies and (B) mean swim distances to the submerged platform over 10 days of training. Performance of each cohort gradually improved over 10 days, eventually becoming asymptotic by day 10. (C) Swim speeds of older mice were significantly slower and swim distances significantly longer, suggesting that the appropriate index to evaluate spatial learning ability is swim distance. (D) Mean number of platform crossings during the probe test, which was carried out 1 day after the completion of training. (E) Mean time spent in the training quadrant during the probe test. In 22-month-old mice, platform crossings were significantly fewer than in younger mice, suggesting that 22-month-old mice were significantly impaired. (F) Mean escape latencies and (G) mean swim distances to the visible platform during cued training. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001.