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October13,2016
Sex
•
Why‘worry’aboutreproductivebehaviors?
-Sex/love:atthebasesofmanysocialinteractions.Atthebasesofart
production(literature,painting…)
-Sexualbehavior(sex)vs.sexualexperience(emotion):twodifferent
(interacting)neuralsystems.Consequences:physicalandpsychological
-sexuallydimorphicbehaviors:somedifferencesbetweenmale/female
behaviorsareduetoatleastpartofsexdifferences
-whataretheneutralstructuresthatareinfluencedbysexdifferences?What
psychologicalfunctionsmightbeaffectedbysexdifferences?How?
-sexualorientation:Howmuchis‘psychology’?Howmuchis“biology”?
GeneticSex
• Geneticfactors
-gametes=ova+sperm.23chromosomeseachàtotalof23pairs
-1pairofsexchromosomes
-thex-rating!:3x-onlygametesbut50%XY
• Geneticsexisdeterminedbythemalegametes
Sex
Ychromosomeàactivateotherchromosomesàsexdifferences
• Gonads
-testes+ovaries:producesperm,ovum,andhormones
-1geneontheYchromosomewilltriggertestesdevelopment(SRYgene)
-gonadsarephysicallydifferentiated6weeksafterconception,functionally
differentiatedafter3monthsgestation
-aftergonaddevelopment:organizationalvs.activationalhormonaleffects
• SRYTesting:genderverification:wasabandonedin2000,singlegenesare
notreliableindicatorsofsex/gender
-SRYisthemaledeterminationfactor
Sex:InternalGenitalia
• Internalsexorgans
MullerianandWolffiansystems
Malegonads(testes)produce:
-anti-mullerianpeptidehormones(defeminizing)
-pro-wolffiansteroidhormonescalledandrogenssuchastestosterone
ordihydrotestosterone(masculinizing)
USCensus1996:Males:48.9%
Females:51.1%
Geneticdisorders:
-androgeninsensitivitysyndrome(XY:lookfemalebutnofemaleinternalorgans)
-persistentmullerianductsyndrome(XY:lookmalebutinternallybothmaleand
female)
-TurnerSyndrome:XO(lookfemaleinternallyandexternally,butnogonads)
Sex
•
ExternalSexOrgans
-primarysexcharacteristics(birth):gonads,internalgenitalia,external
genitalia
-secondarysexcharacteristics(puberty):facialhair,breasts
Sex:Puberty
• Puberty
Gonadotropin-releasinghormones
gonadotropichormones
Note:Infemales,pubicandaxillaryhairdependonadrenalgland(kidney)
• CNS/PNSSexcontrollers
-hypothalamusandamygdala:sexandemotion(nextchapter)
Sex:HormonalControl
• Hormoneshaveactivationalandorganizationaleffects.Theyalsoactonthe
nervoussystemàsexuallydimorphicbehaviors
HormonalCycles:females
-estrouscycle:lastseveraldays,onlyaperiodofmating
-menstrualcycle:monthlygrowth/lossofliningofuterus.Mattingatanytime.
Progesterone:liningofuterus,inhibitsfurtherovumproduction.Ifthereis
nofertilizationàdecreaseàlossofliningàmenstruation
Notes:
-womenarebornwithovumandloseovumthroughoutlife
-menaren’tbornwithspermandgainspermthroughoutlife
Sex:HormonalControl
MaleSexualBehavior
Intromissionàpelvicthrustingàejaculationàrefractoryperiod
Coolidgeeffect:decreaseofrefractoryperiodwiththeintroductionofnewfemales
FemaleSexualBehavior
• Lordosis
-3measuresofsexualbehaviors:
attractiveness:changeinmalebehavior
proceptivity,receptivity:changeinfemalebehavior
• Androgens(testosterone)haveorganizationaleffectsonbehavior
• Testosteroneimmediatelyafterbirthhasbehavioraldefeminizationand
later,behavioralmasculinizationeffects
Pheromones
-sexualcommunicationsbetweenindividuals,VomeroNasalorgan
Animals:
-VNO:sensitivetourine(rat)
-DamageofVNO:poordiscriminationbetweenmoleandfemale(mice)
-Singleneuronsinaccessoryolfactorybulbcanselectivelyrespondtomaleand
femalescents(rodents)
Humans:
-T-shirtsmellàmale/femalediscriminationsinhumans
-Inhumans:sweatcarriessexuallydimorphicmolcules
Pheromones:ExperimentalEvidences
-Lee-Booteffect:groupsofco-housedfemalemiceàstopofestroussystem
-Whitteneffect:synchronizationofestrouscycle,ifmaleodorpresent
-Vendenbergheffect:earlyonsetoffemalepubertyuponexposuretomale
pheromones
-Bruceeffect:femalemouseinseminatedexposedtonewmale(contacttestes)
àfailedpregnancy
-classroomseatingeffect:possiblyanecdotal…