Sexual Differentiation of the Brain

Exposure to hormones during different periods of development can dramatically change both behavior and brain morphology. Studies in rodents have suggested that exposure to testosterone during a critical period near the time of birth can masculinize certain areas of the central nervous system (CNS) as well as behavior (most notably sexual behavior). Some areas of the CNS remain susceptible to the influence of hormones beyond this critical period, with morphological changes occurring in adolescence, adulthood, or both. The human CNS is also sexually differentiated, although the influence of hormone exposure on behavior is less well established than in nonhuman models.