生物心理學課件-chapter

Chapter8：Sex:Evolutionary,HormonalandNeuralBsasesSexualWhyAreThereTwoSexualSexualReproductiveBehaviorCanBeDividedintoFourSexual bringthemaleandfemaleInmanyspeciesanindividualisattractivetoothers,andisitselfattractedtoothers,onlywhenitsbodyisreadytoreproduce.Gauge(測量)howattractiveafemale/maleisbyobservinghowmales/femalesrespondtoher—howrapidlytheyapproachhowhardtheyworktogainaccesstoher,andsoon.Appetitivebehaviors:behaviorsthatestablish,maintain,orpromotesexualapproach,remainclose,sniff,song,Copulation(Coitus):intromission,CopulationbringsgametestogetherforCoolidge copulatoryHormonesplayanimportantroleinanimalsmatingactivationaleffect:thehormonetransientlyinfluencesThebloodlevelsoftestosteronenotresponsibleforthedifferenceinthevigor(matewithareceptivefemale)averysmallamountoftestosteroneisenoughtomaintainthematingInducesexualreceptivityinfemalebyinjectingwithestrogen(雌激素TheNeuralCircuitryoftheBrainRegulatesReproductiveMostofwhatweknowabouttheneuralcircuitryunderlyingreproductivebehaviorscomesfromanimalmodels,especiallyrates.Inawiderangeofvertebratespecies,steroidreceptorsareconsistentlyfoundinmanybrainregions,includingthehypothalamus,medialamygdala,andhippocampus,amongmanyother.Steroideffectsinthehypothalamusplayacentralroleinregulatingbehavior,andthese’sreasontobelievethatthisistrueofhumanasSteroidsActontheHypothalamustoPromoteFemaleSteroidautoradiographyindicatedthatthehypothalamuscontainsacenterforestrogen‐andprogesterone‐sensitiveneuronsTheroleoftheventromedialhypothalamus(VMH)istomonitorsteroidhormoneconcentrationsand,attherighttimeintheovulatorycycle,activateamultisynapticpathwaythatinducesthespinalcordtocontractbackmuscles,producingalordosisresponsethatisotherwiseabsent.TheVMHwasfoundtobecrucialforlordosisbecauselesionsthereabolishtheresponse.Tinyimplantsofestradiol(雌二醇intheVMHcaninduceEstrogencanincreasethesizeofthedendritictreesofVMHEstrogeninducetheproductionofprogesteronereceptors,andactivatedTheVMHsendsaxonstotheperiaqueductalgray(PAG),wherelesionsgreatlydiminishlordosis.PAGneuronsprojecttothemedullaryreticularformation,whichinturnprojectstothespinalcordviathereticulospinaltract.AndrogensActivateaNeuralSystemforMaleReproductiveHypothalamicmedialpreopticarea(視前區(qū)(mPOAischock‐fullsteroid‐sensitiveCastrate&NeuronsinthemPOAsendtheiraxonstotheventralmidbrainviathemedialforebrainbundle.Fromthere,informationgoestothebasalgangliaand,throughadiffusemultisynapticpathway,tothespinalThespinalcordmediatesthevariousreflexesofintromissionandReceptivefemalereleasepheromonesthatcanbedetectedbythemale’svomeronasalorganandarousethemale,asevidencedbypenileThevomeronasalinformationfromtoaccessoryolfactorybulbtothemedialamygdala,whereinturnsendsaxonstothemPOAappearstointegratehormonalandsensoryinformationsuchaspheromones,andtocoordinatethemotorpatternsofcopulation.HumanReproductionBringsGametesTheHallmarkofHumanSexualBehaviorIs tandardizedsetofThemostcommoncoitalposturesisface‐to‐faceTypicalresponsepatternsofhumanasconsistingoffourIncreasingexcitement:thephallus esengorgedwithblood,makingiterect.theparagigantocellularnucleus(PGN,旁巨細胞核)inponssendsserotonergic(素)fibersdownthespinalcordthatinhibiterection,andsexuallyarousedforebraininhibitsthePGN,permittingerectionGenderThegreatervarietyofcommonlyobservedsequencesinMenhaveonlyonebasicpattern,womenhavethreetypicalMostmenhaveanabsoluterefractoryphaseSomeDiseasesCanBeTransmittedthroughSexualHuman HormonesPlayOnlyaPermissiveRoleinHumanSexualAndrogensindeedstimulatesexualactivityinmen(double‐blindTestosteronelevelsbelownormalaresufficienttorestorebehavior,andthereisnocorrelationbetweensystemicandrogenlevelsandsexualactivityamongmenwhohavesomeandrogenAndrogensmayalsoactivatesexualinterestinSexualbehaviorvarieswiththemenstrualcyclePheromonesBothPrimeandActivateReproductiveSexualactivationcanbethoughtofascommunicationbetweenthegonadsandthebrain(insidetheindividual)Hormones soprovideinformationbetweenrapidandbriefactivation(E.g. TheFprostaglandin(素)offemalePrimeseffect:aggression/blockingofWhyAreThereTwoSexualReproductionHelpsCombineBeneficialthefunctionofsexualreproductionistobringmanybeneficialmutations(突變together,eachofwhicharoseindifferentThemixingofbeneficialgenescertainlygeneratesbiologicalproducingnewcombinationsofgenesthatmaybettersurvivethenewSomeanimalscanreproducebyeitherMalesandFemalesOftenAdoptDifferentReproductive ManySomeManyMostGenderMalesarenotalwaysthelargerNervoussystemsdisplaysexualMalegametesaresmallandcheap,femalegameteslargeandCourtshipisaperiodduring,whichthefemaleindirectlyassessesthegeneticmakeupofamaltojudgehissuitabilityasamate.Sexualselection:aspecialtypeofnaturalselection—MatingSystemsCanBeClassifiedintoFourBasicPromiscuity:withseveralpartnersanddonotestablishlong‐lastingPolygyny:onemalematingwithagroupPolyandry:eachfemaleofthespeciesmateswithseveralSexualTheSexofanIndividualIsDeterminedEarlyinThepathofsexualdifferentiationissetbythe 異形),theyhavetwodifferentsexchromosome(XY)Female—homogametic同配子),theyhavetwosamesexchromosomeSexChromosomesDirectSexualDifferentiationoftheInmammalstheYchromosomecontainsagenecalledtheSRYgenesex‐determiningregionontheYIfanindividualhasaY,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,ortheBehaviorismu oredifficultthanphysicalfeaturestodefineasfeminineorFeaturesmayconfusing(e.g.,PartsofbrainaretypicallydifferentbetweenthesexesinhumanandotherGonadalHormonesDirectSexualDifferentiationoftheBrainandEarlyTesticularSecretionsResultinMasculineBehaviorinOrganizationalhypothesis(1959,WilliamC. Steroidshaveanorganizationalinfluenceonlyduringearlydevelopment(—sensitiveperiod)andtheeffectispermanent,inadulthoodtheyexertanactivationaleffect,temproarilyinfluencingbehavior.Thenervoussystemisatypeoftissuelisteningfortheandrogenicotherwise,willorganizeitselfinafeminineTheEstrogenicMetabolitesofTestosteroneMasculinizetheNervousSystemandBehaviorofRodentsWhennewbornfemaleratsweretreatedwithverysmalldoseofestrogenscouldpermanentlymasculinizebehaviors;whereasachievingthesameeffectwithtestosteronerequiredahigherdose.Themajorandrogen(testosterone)andthemajorestrogen(estradiol)differbyonlyonemolecule.SeveralRegionsoftheNervousSystemDisplayProminentSexualSongcontrolregionsinmalesongbirds(malelargerthanThepreopticarea(POA)ofrats(sexuallydimorphicnucleusoftheThespinalcordinmammals(spinalnucleusofthebulbocavernosus球海綿體),SNB)SocialInfluencesAffectSexualDifferentiationoftheNervousTheSNBsystemoffersanilluminatingexampleofhowsocialfactorscanmediatethemasculinizationproducedbysteroids.thedamtreatsapupdifferentlybecausehe’samaleandtherebymasculinzeshisdevelonervoussystemwhataboutineveryculturemostpeopletreatboysandgirlsdifferently——societyaffectssexualdifferentiationofthebrainandbehavior ’ssexualSomepeopledevelopromanticatta entstoandyearnto withaofthesamesex.(Why?)View1:Thissexorientationisbasedoninfantsobservingtheadultsaroundthemandmodelingtheirbehavioronthebehavioroftheoppositesex,ratherthantheirown.It’spossiblethatearlysocialexperienceaffectsthedevelopmentINAH‐3todeterminelatersexualSexualexperiencesasanadultcouldaffectINAH‐3structure,sothesmallernucleusinsomehomosexualmenmaybetheresultoftheirhomosexuality.(?)Homosexualmenandwomenaremorelikelytobeleft‐handedthanheterosexualmenandwomen—androgenscannotbethewholestoryFemalePrenatal(出生以前的)androgensmayormaynotactonthebrain,buttheycertainlyactontheperiphery(外表面).Somepeopleseemtochangesexatpuberty(WhysomepeopleraisedasgirlslaterbehaveasThesocialinfluencesofgrowingView2: somethinghappenstothefetalbraintodeterminelaterorientation——”somepeopleareborngay”Ifwedepriveamaleratofandrogensatbirth,wecanbesurethathewilldisplaylordosis(afemalebehavior)inresponsetoanothermaleinPostmortemexaminationsonthebrainofhomosexualmen,heterosexualmen,andwomen,andfoundthatthePOAcontainsanucleus(INAH‐3)thatislargerinmenthaninwomenandlargerinheterosexualmenthaninhomosexualmen.View1&ViewThereportsthatsexualorientationisEstimatesarethatabouthalfthevariabilityinsexualorientationisduetodifferencesintome(comefromtheirmother’sXBothgeneticandenvironmentalinfluencesaffectsexualorientationinhumansDespiteextensiveefforts,noonehascomeupwithareliabletochangeaman’ssexualReproductivebehaviorsaredividedintofourstages:sexualattraction,appetitivebehaviors,copulation,andpostcopulatorybehaviors,includingparentalbehaviorsinsomespecies.Thebrain ernsthetimeatwhichtheorganismshouldreproduceandusesproteinhormonestoinducethegonadstoproducegametes.Thegonadsinturnproducesteroidhormonesth tivatethebraintoincreasetheprobabilityofreproductivebehaviors.Inhumans,verylowlevelsoftestosteronearerequiredforeithermanorwomentodisplayafullinterestinmating,butadditionaltestosteronehasnoadditionaleffect.Thereforethereisnocorrelationbetweencirculatingandrogenlevelsandreproductivebehaviorsinmen.NoristhereanystrongcorrelationbetweencopulatorybehaviorandstageofthemenstrualcycleinHumancopulatorybehaviorisremarkablyvaried.Attemptsatclassificationofthestagesofcopulationinhumanssuggestthatmostmenshowasinglepattern,whilemostwomendisplayoneofthreebasicpatternsofsexualresponse.Forbothsexes,thefourbasicstagesofthesexualresponsepatternare(1)increasingexcitement,(2)plateau,(3),and(4)Summary—WhyaretheretwoSexualreproductionbringstogetherinasingleindividualthebeneficialmutationsthathaveariseninseparateindividuals.Insomespecies,sexualreproductionhasledtotheevolutionofindividualsspecializedtoreproduceaseitheramaleorafemale.Sexualdifferentiationduringdevelopmentthenallowsmalesandfemalestodevelopdifferentbodiesandbrains.Maleandfemalesvertebratesmakedifferentinvestmentsintheiroffspring;consequently,mostmalesofmostspeciesarepromiscuous,andmostfemalesofmostspeciesareverydiscriminatinginchoosingmates.Thissituationleadstosexualselectionpressuresthat,overtime,canexaggeratesexualTherearefourdifferenttypesofmatingsystems:(1)promiscuity(bothsexesmatewithmultiplepartners),(2)polygyny(eaalemateswithmultiplefemales),(3)polyandry(eachfemalemateswithmultiplemales),and(4)monogamy(asinglemaleandasinglefemaleformalastingbond)Invertebrates,geneticsex(determinedbythepresenceorabsenceofaYchromosomeinmammals)determineswhethertestesorovariesdevelop,andhormonalsecretionsfromthegonadsdeterminewhethertherestofthebody,includingthebrain,developsinafeminineormasculinefashion.Inthepresenceoftesticularsecretionsamaledevelops;in