资源描述：
《18 Homeostatic Synaptic Plasticity 》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、HomeostaticSynapticPlasticityGinaTurrigianoBrandeisUniversity,DepartmentofBiologyandCenterforBehavioralGenomics,Waltham,MA02454,USA,turrigiano@brandeis.eduAbstract.Homeostaticsynapticplasticitymechanismsprovideameansforneuronsandcir-cuitstomaintainstablefunctioninthefaceofperturbationss
2、uchasdevelopmentaloractivity-dependentchangesinsynapsenumberorstrength.Theseformsofplasticityusenegativefeedbacksignalingtoadjustsynapticpropertiestokeepactivityclosetosomeinternalsetpointvalue.Recentworksuggeststhattherearelikelymultipleformsofsynaptichomeostasis,mediatedbydistinctsign
3、alingpathwaysandwithdistinctexpressionmechanisms.Bothexci-tatoryandinhibitorysynapsesaresubjecttohomeostaticregulation,andtheformofplasticitypresentataparticularsynapselikelydependsonitsfunctionwithinaneuronalcircuit.1Introduction“Somehowtheunstablestuffofwhichwearecomposedhaslearnedthe
4、trickofmaintainingstability.”-WalterCannon,TheWisdomoftheBody,1932Nervoussystemsarefacedwithafundamentalproblem:howtoallowplasticmechanismstoshapetheiroutputandfunction,withoutcompromisingthestabilityandintegrityoftheunderlyingcircuitsthatdrivebehavior.Manyoftheplasticchangesthatunderli
5、edevelopmentalandlearning-relatedadaptationsarethoughttorequiresynapse-specificchangesinsynapticstrengths,yettheseprocessesexertapowerfuldestabilizinginfluenceonnetworkfunction(1,56).“Hebbian”(afterDon-aldHebb)formsofsynapticplasticity,suchaslong-termpotentiation(LTP)andlong-termdepress
6、ion(LTD),strengthensynapticinputsthatareeffectiveatdepolar-izingthepostsynapticneuron,andweakeninputswhosefiringisnotcorrelatedwiththepostsynapticneuron.Suchcorrelation-basedmechanismsareproblematic:byanalogytounconstrainedcapitalism,therichcontinuallygetricher,andthepoorgetpoorer.Forex
7、ample,inthesynapticarenathishappensbecausestrongsynapsesthatareeffectiveatdepolarizingthepostsynapticneuronwillcontinuetobestrength-ened,andwillthusbecomebetterabletodepolarizethepostsynapticneuron,initiat-inganunconstrainedpositivefeedbackcycle.J.W.Hell,M.D.Ehlers(eds.),Struct
