Our studies have shown that both stress-induced, enhanced secretion of corticosterone and adrenalectomy-induced, reduced secretion of corticosterone are associated with impaired spatial memory performance. On the other hand, estradiol administration is associated with enhancements in spatial memory performance. Although these changes in performance are small, they are consistent with structural changes induced by these hormones (or their lack) on specific cells within the hippocampus which form the tri-synaptic loop (a summary of the behavioral and morphological effects is shown in Figs. 1 and 2). Thus, these results suggest that the morphological changes induced by the hormones have an impact on hippocampal function. Important goals of future studies are to seek ways to maximize gonadal hormone-dependent enhancements in memory function and to minimize adrenal steroid-dependent impairments in memory function as well as to understand the mechanisms behind these behavioral and morphological changes.