Figure 4.

Effects of PREG S bilateral infusion into the hippocampus on the performance of impaired aged rats in the Y-maze. Impaired male rats, 22 months old (n = 12) were split into two subgroups and received infusion of PREG S or vehicle. Vehicle injection had no effect on the performances of impaired rats (n = 6) in the Y-maze (ITI = 6 h). In contrast, the subgroup treated with PREG S (n = 6) performed significantly above chance level 6 h postinjection (t = 4.1, df = 5, ∗∗, P < 0.01), but returned to chance level 7 days later (t = 1.1, df = 5, ns).