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Hormones Sexual Behavior

benjamin
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Hormones Sexual Behavior

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    1. Hormones & Sexual Behavior Lecture 24

    3. Female behavior: rats Receptive - lordosis head down haunches up Proceptive ear wiggling darting Hopping ~

    4. Male behavior: rats Mounts no testosterone ? no mounting Intromits several times Ejaculates 4-5 times 5 min refractory period ~

    5. Organizational Effects of Hormones SDN & SNB Critical periods Humans - prenatal Rats - perinatal easily manipulated ~

    6. Hormones: Sexual Behavior Castrate XY males at birth Later... testosterone ? no male behavior estrogen? lordosis Brain not masculinized ~

    7. Hormones: Sexual Behavior Ovariectomize female at birth give testosterone Later... estrogens ? no female behavior testosterone ? male behavior Brain masculinized ~

    8. Human Sexual Behavior No stereotypical M & F behaviors Men are like rats T plays a activational role Castration decline in sexual behaviors variable rate Role of oxytocin? probably not knockout mice ~

    9. Hormones - Women Estrogen & Progesterone no activational effects Ovariectomy has no effect Some fx on willingness to copulate increased during ovulation E & P are high ~

    10. Hormones - Women Testosterone levels correlated with frequency of intercourse Oxytocin uterine and vaginal contractions sensations associated with orgasm ~

    11. Brain Mechanisms: Rats Medial preoptic area lesion SDN ? no M sexual behavior NOT sexual motivation Bar press for female ~

    12. Brain Mechanisms: Rats Ventromedial nucleus lesion- no female sexual behavior Masculinizes by preventing cell death Amygdala lesion ? increased sexual behavior Indiscriminate ~

    13. Homosexuality Sex hormones role? rats - yes Humans? NOT SURE Learning experiences? or biologically determined? ~

    14. Biological Factors Levels of circulating sex hormones? No Differences in brain structure? Perhaps - Where? ~

    15. Homosexuality Simon LeVay Brains of male AIDS victims Anterior Hypothalamus Anterior commissure SDN (rats) Humans: 3rd interstitial nucleus ~

    16. Anterior commissure larger in females Similar relationship ~

    17. Homosexuality 2 Hypotheses 1. Androgen levels low in XY fetuses that ? gay high in XX fetuses ? lesbian 2. Genetic differences in fetal brains response to androgens Xq28 - tip of the X chromosome shared by large % of gay brothers ~

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