The time in the quadrant containing the platform, and the number of quadrant & platform crossings, in the probe trial, by young adult rats or 2-year old rats. On the day after the last test to find the platform (session 5 in Fig. 1), the rats were given a probe test. In the probe test, the platform was removed, and the rats were allowed to swim in the tank for 1 minute. (A) The amount of time the rats spent in the quadrant that had contained the platform (mean±s.e.m.). (B) The number of times the rats crossed the position of the platform, plus the number of times the rats entered the quadrant that had contained the platform (mean±s.e.m.).