In humans and other primates, testosterone acts on the hypothalamus directly instead of by conversion to estradiol. However, the final mechanism in terms of prostaglandins, PI3, and so forth are the same in rodents.It is possible for one area of the hypothalamus to become more masculinized or more feminized than another. Because genes vary, and so do factors of epigenetic changes, very few people have a brain that is male-typical or female-typical in all regards. Instead, almost anyone’s brain is a mosaic of male-typical, female-typical, and approximately neutral areas.oSex Differences in PlayPreferences tend to be consistent over time. Children who show the greatest performance for boy-atypical activities at age 3 usually show the greatest amount of boy-atypical activities at age 13. Likewise, for girls.Much of this pattern results from socialization. However, socialization need not be the whole story. It may be that parents give those toys because previous generations found that boys and girls often differ in their interests from the start.There may be a predisposition for boys and girls to prefer different types of toys.Two studies correlate chemicals in the mother’s blood during pregnancy with their children’s choices of toys years later.The girls exposed to higher testosterone levels in prenatal life showed slightly elevated preferences for boy toys.Phthalates inhibit testosterone production in pregnant women. On average, sons of women with high phthalate levels showed less interest in typical boys’ toys, and more interest in typical girls’ toys.Prenatal hormones, especially testosterone, alter the brain in ways that influence differences between boys and girls in their activities and interests.It is possible for girls to develop a condition called congenital adrenal hyperplasia as a result of very high testosterone levels before birth. Compared to other girls, they are less likely to imitate what a woman or young girl does, and less likely to be influenced by information that certain things are intended for girls. Activating Effects on Sex Hormones
-At any time in life, current levels of testosterone or estradiol exert activating effects, temporarily modifying behavior. Behaviors can also influence hormone secretions.-The pituitary hormone oxytocin is also important for reproductive behavior. oIt stimulates contractions of the uterus during birth, and it stimulates the mammary gland to release milk. Also present during/after orgasm.oMalesTestosterone, essential for male sexual arousal, acts partly by increasing touch sensitivity in the penis.Sex hormones also bind to receptors that increase responses in parts of the hypothalamus, including the ventromedial nucleus, the medial preoptic area (MPOA), and the anterior hypothalamus.