Steroid Hormone Modulation of Hippocampal Dependent Spatial Memory.

Recent studies show that the adult CNS is capable of considerable re-structuring and re-growth, a property previously thought limited to the developmental period. Hormones play an important role in many of these plastic processes, and the hippocampus, as a target for all the major classes of steroid hormones, undergoes considerable remodeling. Since it is critical for mediating tasks requiring spatial memory, the hippocampus can serve as an important model for understanding not only the mechanisms underlying plasticity of brain circuits but also how these changes impact on a higher order function, spatial memory. In this review, the effects of steroid hormones on hippocampal remodeling are discussed, and the ability of estradiol to enhance spatial memory as well as the ability of both excessive or diminished corticosteroid levels to impair spatial memory are described. The neural mechanisms for these effects, as well as previous and current contributions of McEwen and colleagues to this expanding area of research, are discussed.