Psych 2210 1st Edition Lecture 14 Outline of Last Lecture I. Structural Sexual DimorphismsII. Behavioral Sexual DimorphismsIII. Fetal Hormones and Sexual OrientationIV. Male ProcessV. Steps in Female PhenotypeVI. Clinical cases Outline of Current Lecture I. Working HypothesisII. PredictionsIII. Sexual Orientation as Sexually Differentiated TraitIV. Experimental EvidenceV. ConclusionVI. What About Humans? VII. Relationship between prenatal testosterone levels and sexual orientation in humansVIII. John/Joan Case StudyIX. Genetic and Immunological FactorsCurrent LectureI. Working Hypothesis: sexual orientation is a sexually differentiated behavioral feature influenced by the prenatal hormonal environmentII. Predictions: a. Low prenatal testosterone: attraction to malesb. High prenatal testosterone: attraction to females III. Sexual Orientation as Sexually Differentiated Traita. Male and female mammals are normally exposed to different pre-natal hormonal environmentsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Males: high testosterone ii. Females: low testosteroneb. Result in organizational effects on body and behavior—e.g. SDN-POAc. Is homosexuality found in animals? Yes. Every species studied seems to show same sex attraction. Homosexuality found across species. d. Is it linked to organizational effects? i. Organizational effects determine preference1. Partner preference determined by prenatal hormones2. Hormonal manipulations during sensitive period can reverse typical orientationa. Blocking testosterone in male ratsb. Increasing testosterone in female ratsIV. Experimental Evidencea. Prenatal testosterone to female rats during critical period: i. Approach and attempt to mate with female rats in adulthoodb. Blocking testosterone to male rats in sensitive period: i. Receptive to male rats in adulthoodV. Conclusiona. Presence of high testosterone levels in sensitive period results in: i. Male-typical sexual behaviorii. Larger SDN-POAiii. Supports Ellis- Ames HypothesisVI. What about Humans? a. 1. Do prenatal hormones have organizational effects on human brain structures? b. 2. Do prenatal hormones have organizational effects on sexual orientation?c. Sexual Dimorphism in humansi. Testosterone clearly controls the differentiation of male-typical external and internal genital structures. VII. Relationship between prenatal testosterone levels and sexual orientation in humansa. CAH (congenital adrenal hyperplasia) Womeni. High prenatal testosteroneii. 33% self-identify as lesbian as adultsb. AIS individuals i. XY genotype, but low pre-natal testosterone environmentii. Female gender identityiii. Sexually attracted to males iv. Sexual orientation not linked to genetic sex, but to prenatal hormones c. 5-alpha-reductase deficiencyi. Prenatal environment: high testosteroneii. Social postnatal environment: raised as girlsiii. Adult sexual orientation: self-identify as male, attracted to females iv. What would social construction view predict? d. Markers for prenatal testosteronei. 2D-4D ratio1. Biomarker for embryonic exposure to testosterone in the human fetus2. Males: index finger shorter than ring fingera. Higher prenatal testosterone levels 3. Females: index finger longer than ring fingera. Lower prenatal testosterone levels4. CAH females: a. 2d-4d: masculinized patternb. Orientation: more likely to identify as lesbian5. Lesbian women: a. 2d-4d: masculinized patternb. Suggests: lesbians have, on average, been exposed to higher concentrations of androgens during development c.ii. Oto-Acoustic emissions (OAE)1. Movements of the tympanic membrane2. Faint sound when inner ear is stimulated3. Sexual dimorphism: response is stronger in women than in men in all species 4. Though to reflect prenatal testosterone5. Lesbian women: a. Significantly weaker in lesbians compared with heterosexual womenb. Suggesting lesbian women were exposed to higher concentrations of androgens during early life. 6. Gay men: a. Same as in heterosexual men. iii. Brain structural differences between men and women 1. INAH-32. LeVay studya. INAH-3-POA: analogous to SDN-POA in other mammalsb. Sexual dimorphism: INAH-3 larger in men than in womenc. Sexual orientation: larger in heterosexual men than in homosexual mend. Summary: did control for possible confound with AIDS, correlational study: can’t determine cause and effect. No attempted replications. VIII. John/Joan Case Studya. Raised one of her children as female after circumcision incidentb. John Money: Social constructivisti. Advised them to raise Bruce as a girl ii. Reported as “successful” iii. Never actually identified as a girl iv. “Brenda” did not identify as a girl –changed to Davidv. By the age of 15, Brenda was suicidal and told her parents she would kill herself if they made her go see Dr. Money again. c. Implicationsi. Sexual orientation strongly influenced by pre-natal testosterone levelsii. Gender identity developed at very early age. IX. Genetic and Immunological Factorsa. Twin studiesi. Identical male twins: 50-65% concordanceii. Fraternal twins: 20-25% concordanceiii. General population rates: 5-6% iv. Same for female twinsv. Genes, rather than environment: identical twins raised apartb. Specific Gene?i. Hamer Studies1. Studied pairs of gay brothers2. Looked for candidate genes on X chromosome3. Sexual orientation in men tends to be transmitted through the mother’s side ii. Results: gay brothers likely to share a market located in the long arm of the X chromosome, a region called Xq28iii. Other studies have identified other potential