Epigenetic turn ons and turn offs: chromatin reorganization and brain differentiation.

The study of epigenetics allows for the understanding of gene × environmental interactions and provides a mechanism by which brief internal or external environmental changes can shape lasting differences in gene function and behavior. Epigenetic processes appear to impact a wide variety of physiological processes within the developing brain, including neuroendocrine function. An epigenetic model is proposed by which steroid hormones and the social environment induces appropriate masculinization of the brain by turning on and off gene transcriptional events. This minireview will discuss how epigenetic events influence sexual differentiation of the brain and point at examples suggesting that some epigenetic events can be quite dynamic.