生物心理學(xué)課件-chapter

Chapter8：Sex:Evolutionary,HormonalandNeuralBsasesWhyAreThereTwoReproductiveBehaviorCanBeDividedintoFourSexual bringthemaleandfemaleInmanyspeciesanindividualisattractivetoothers,andisitselfattractedtoothers,onlywhenitsbodyisreadytoreproduce.Gauge測(cè)量howattractiveafemale/maleisbyobservingmales/femalesrespondtoher—howrapidlytheyapproach,howhardtheyworktogainaccesstoher,andsoon.sexskin—estrogen(雌激素Appetitivebehaviors:behaviorsthatestablish,maintain,orpromotesexualapproach,remainclose,sniff,song,nest-Copulation(Coitus):intromission,CopulationbringsgametestogetherforexternalinternalRefractory copulatoryparentalHormonesplayanimportantroleinanimalsmatingactivationaleffect:thehormonetransientlyinfluencesThebloodlevelsoftestosteronenotresponsibleforthedifferenceinthevigor(matewithareceptivefemale)averysmallamountoftestosteroneisenoughtomaintainthematingInducesexualreceptivityinfemalebyinjectingwithestrogen(雌激素TheNeuralCircuitryoftheBrainRegulatesReproductiveMostofwhatweknowabouttheneuralcircuitryunderlyingreproductivebehaviorscomesfromanimalmodels,especiallyrates.Inawiderangeofvertebratespecies,steroidreceptorsareconsistentlyfoundinmanybrainregions,includingthehypothalamus,medialamygdala,andhippocampus,amongmanyother.Steroideffectsinthehypothalamusplayacentralroleinregulatingcopulatorybehavior,andthese’sreasontobelievethatthisistrueofhumanaswell.SteroidsActontheHypothalamustoPromoteFemaleSteroidautoradiographyindicatedthatthehypothalamuscontainsacenterforestrogen-andprogesterone-sensitiveneuronsTheroleoftheventromedialhypothalamus(VMH)istomonitorsteroidhormoneconcentrationsand,attherighttimeintheovulatorycycle,activateamultisynapticpathwaythatinducesthespinalcordtocontractbackmuscles,producingalordosisresponsethatisotherwiseabsent.TheVMHwasfoundtobecrucialforlordosisbecauselesionsthereabolishtheresponse.Tinyimplantsofestradiol(雌二醇intheVMHcaninduceEstrogencanincreasethesizeofthedendritictreesofVMHEstrogeninducetheproductionofprogesteronereceptors,andactivatedTheVMHsendsaxonstotheperiaqueductalgray(PAG),wherelesionsgreatlydiminishlordosis.PAGneuronsprojecttothemedullaryreticularformation,whichinturnprojectstothespinalcordviathereticulospinaltract.AndrogensActivateaNeuralSystemforMaleReproductiveHypothalamicmedialpreopticarea(視前區(qū)(mPOAischock-fullofsteroid-sensitiveneuronsCastrate&NeuronsinthemPOAsendtheiraxonstotheventralmidbrainviathemedialforebrainbundle.Fromthere,informationgoestothebasalgangliaand,throughadiffusemultisynapticpathway,tothespinalThespinalcordmediatesthevariousreflexesofintromissionand(Receptivefemalereleasepheromonesthatcanbedetectedbythemale’svomeronasalorganandarousethemale,asevidencedbypenileThevomeronasalinformationfromtoaccessoryolfactorybulbtothemedialamygdala,whereinturnsendsaxonstothemPOAappearstointegratehormonalandsensoryinformationsuchaspheromones,andtocoordinatethemotorpatternsofcopulation.HumanReproductionBringsGametesTheHallmarkofHumanSexualBehaviorIsAlfredconstructastandardizedsetofThemostcommoncoitalposturesisface-to-faceTypicalresponsepatternsofhumanasconsistingoffourIncreasingexcitement:thephallus esengorgedwithblood,makingiterect.theparagigantocellularnucleus(PGN,旁巨細(xì)胞核inponsserotonergic(素)fibersdownthespinalcordthatinhibiterection,andsexuallyarousedforebraininhibitsthePGN,permittingerectionGenderThegreatervarietyofcommonlyobservedsequencesinMenhaveonlyonebasicpattern,womenhavethreetypicalMostmenhaveanabsoluterefractoryphaseSomeDiseasesCanBeTransmittedthroughSexualHuman HormonesPlayOnlyaPermissiveRoleinHumanSexualAndrogensindeedstimulatesexualactivityinmen(double-blindTestosteronelevelsbelownormalaresufficienttorestorebehavior,andthereisnocorrelationbetweensystemicandrogenlevelsandsexualactivityamongmenwhohavesomeandrogenAndrogensmayalsoactivatesexualinterestinSexualbehaviorvarieswiththemenstrualcyclePheromonesBothPrimeandActivateReproductiveSexualactivationcanbethoughtofascommunicationbetweenthegonadsandthebrain(insidetheindividual)Hormonescanalsoprovideinformationbetweenrapidandbriefactivation(E.g. TheFprostaglandin(素)offemalePrimeseffect:aggression/blockingofWhyAreThereTwoSexualReproductionHelpsCombineBeneficialfission→parthenogenesis→sexualthefunctionofsexualreproductionistobringmanybeneficialmutations(突變together,eachofwhicharoseindifferentThemixingofbeneficialgenescertainlygeneratesbiologicalproducingnewcombinationsofgenesthatmaybettersurvivethenewSomeanimalscanreproducebyeitherHermaphrodites(雌雄同體MalesandFemalesOftenAdoptDifferentReproductive AmazonManySomeManyMostGenderMalesarenotalwaysthelargerNervoussystemsdisplaysexualMalegametesaresmallandcheap,femalegameteslargeandCourtshipisaperiodduring,whichthefemaleindirectlyassessesthegeneticmakeupofamaltojudgehissuitabilityasamate.SexualSelectionAccentuatesDifferencesbetweentheSexualselection:aspecialtypeofnaturalselection—MatingSystemsCanBeClassifiedintoFourBasicPromiscuity:withseveralpartnersanddonotestablishlong-lastingPolygyny:onemalematingwithagroupPolyandry:eachfemaleofthespeciesmateswithseveralTheSexofanIndividualIsDeterminedEarlyinThepathofsexualdifferentiationissetbythe (),theyhavetwodifferentsexchromosome(XY)SexChromosomesDirectSexualDifferentiationoftheInmammalstheYchromosomecontainsagenecalledtheSRYgene(forsex-determiningregionontheYchromosome)IfanindividualhasaY,thecellsinthecoreofindifferentgonadbeginmakingtheSRYprotein.TheSRYproteincausesthecellsinthecoreofthedifferentgonad(themedulla)toproliferate(增生)attheexpenseoftheouterlayers(thecortex),andtheindifferentgonaddevelopsintoa.IftheindividualhasnoY(orhasaY,buttheSRPgeneisdefective),noSRYproteinisproduced,andtheindifferentgonadtakesadifferentcourse:Cellsofthecorticallayersproliferatemorethanthoseofthemedullarylayers,andanovaryforms.GonadalHormonesDirectSexualDifferentiationoftheRestoftheDevelotestesproduceseveralhormones,whileearlyovariesproduceverylittlehormone.Theembryo(),receivethetesticularhormones,willbegindevelomasculinecharacters;otherwise,developfemininecharacters.HowShouldWeDefineGender—byGenes,Gonads,Genitals,ortheBehaviorismuchmoredifficultthanphysicalfeaturestodefineasfeminineorFeaturesmayconfusing(e.g.,androgen-PartsofbrainaretypicallydifferentbetweenthesexesinhumanandotherGonadalHormonesDirectSexualDifferentiationoftheBrainandEarlyTesticularSecretionsResultinMasculineBehaviorinOrganizationalhypothesis(1959,WilliamC.Steroidshaveanorganizationalinfluenceonlyduringdevelopment(—sensitiveperiod)andtheeffectispermanent,inadulthoodtheyexertanactivationaleffect,temproarilyinfluencingbehavior.Thenervoussystemisatypeoftissuelisteningfortheandrogenicotherwise,willorganizeitselfinafeminineTheEstrogenicMetabolitesofTestosteroneMasculinizetheNervousSystemandBehaviorofRodentsWhennewbornfemaleratsweretreatedwithverysmalldoseofestrogenscouldpermanentlymasculinizebehaviors;whereasachievingthesameeffectwithtestosteronerequiredahigherdose.byonlyonemolecule.α-SeveralRegionsoftheNervousSystemDisplayProminentSexualSongcontrolregionsinmalesongbirds(malelargerthanThepreopticarea(POA)ofrats(sexuallydimorphicnucleusofthePOA,Thespinalcordinmammals(spinalnucleusofthebulbocavernosus球海綿體),SNB)SocialInfluencesAffectSexualDifferentiationoftheNervousTheSNBsystemoffersanilluminatingexampleofhowsocialfactorscanmediatethemasculinizationproducedbysteroids.thedamtreatsapupdifferentlybecausehe’samaleandtherebymasculinzeshisdevelonervoussystemwhataboutineveryculturemostpeopletreatboysandgirlsdifferently——societyaffectssexualdifferentiationofthebrainandbehaviorwhatdetermines Somepeopledevelopromanticattaentstoandyearntohavesexwithaofthesamesex.(Why?)View1:Thissexorientationisbasedoninfantsobservingtheadultsaroundthemandmodelingtheirbehavioronthebehavioroftheoppositesex,ratherthantheirIt’spossiblethatearlysocialexperienceaffectsthedevelopmentofINAH-3todeterminelatersexualorientation.SexualexperiencesasanadultcouldaffectINAH-3structure,sothesmallernucleusinsomehomosexualmenmaybetheresultoftheirHomosexualmenandwomenaremorelikelytobeleft-handedthanheterosexualmenandwomen—androgenscannotbethewholeFemalePrenatal(出生以前的androgensmayormaynotactonthebrain,buttheycertainlyactontheperiphery(外表面).Somepeopleseemtochangesexatpuberty(WhysomepeopleraisedasgirlslaterbehaveasPrenataltestosteronemayhavemasculinizedtheirThesocialinfluencesofgrowingView2: somethinghappenstothefetalbraintodeterminelaterorientation——”somepeopleareborngay”Ifwedepriveamaleratofandrogensatbirth,wecanbesurethathewilldisplaylordosis(afemalebehavior)inresponsetoanothermaleinPostmortemexaminationsonthebrainofhomosexualmen,heterosexualmen,andwomen,andfoundthatthePOAcontainsanucleus(INAH-3)thatislargerinmenthaninwomenandlargerinheterosexualmenthaninhomosexualmen.View1&ViewThereportsthatsexualorientationisEstimatesarethatabouthalfthevariabilityinsexualorientationisduetodifferencesinthegenome(comefromtheirmother’sXBothgeneticandenvironmentalinfluencesaffectsexualorientationinhumansDespiteextensiveefforts,noonehascomeupwithareliablewaytochangeaman’ssexualorientationReproductivebehaviorsaredividedintofourstages:sexualattraction,appetitivebehaviors,copulation,andpostcopulatorybehaviors,includingparentalbehaviorsinsomespecies.Thebrain ernsthetimeatwhichtheorganismshouldreproduceandusesproteinhormonestoinducethegonadstoproducegametes.ThegonadsinturnproducesteroidhormonesthatactivatethebraintoincreasetheprobabilityofreproductiveInhumans,verylowlevelsoftestosteronearerequiredforeithermanwomentodisplayafullinterestinmating,butadditionaltestosteronehasnoadditionaleffect.Thereforethereisnocorrelationbetweencirculatingandrogenlevelsandreproductivebehaviorsinmen.NoristhereanystrongcorrelationbetweencopulatorybehaviorandstageofthemenstrualcycleinHumancopulatorybehaviorisremarkablyvaried.Attemptsatclassificationofthestagesofcopulationinhumanssuggestthatmostmenshowasinglepattern,whilemostwomendisplayoneofthreebasicpatternsofsexualresponse.Forbothsexes,thefourbasicstagesofthesexualresponsepatternare(1)increasingexcitement,(2)plateau,(3),and(4)resolution.Summary—WhyaretheretwoSexualreproductionbringstogetherinasingleindividualthebeneficialmutationsthathaveariseninseparateindividuals.Insomespecies,sexualreproductionhasledtotheevolutionofindividualsspecializedtoreproduceaseitheramaleorafemale.SexualdifferentiationduringdevelopmentthenallowsmalesandfemalestodevelopdifferentbodiesandMaleandfemalesvertebratesmakedifferentinvestmentsintheiroffspring;consequently,mostmalesofmostspeciesarepromiscuous,andmostfemalesofmostspeciesareverydiscriminatinginchoosingmates.Thissituationleadstosexualselectionpressuresthat,overtime,canexaggeratesexualTherearefourdifferenttypesofmatingsystems:(1)promiscuity(bothsexesmatewithmultiplepartners),(2)polygyny(eachmalemateswithmultiplefemales),(3)polyandry(eachfemalemateswithmultiplemales),and(4)monogamy(asinglemaleandasinglefemaleformalastingbond)Invertebrates,geneticsex(determinedbythepresenceorabsenceofachromosomeinmammals)determineswhethertestesorovariesdevelop,andhormonalsecretionsfromthegonadsdeterminewhethertherestofthebody,includingthebrain,developsinafeminineormasculinefashion.Inthepresenceoftesticu