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Transcript
MemoryIV PSYC313-Lecture12 Dr.J.Nicol TheEbbinghausForgeEngCurve RetrievalFailure • RetenIoninterval:theamountofImethatelapses betweeniniIallearningandsubsequentretrieval • ForgeEngduetoretrievalfailure:thegreaterthe retenIonintervalthegreaterthelikelihoodthatyour contexthaschangedandthereforethegreaterthe likelihoodofretrievalfailure DecayTheory • MemoriescanfadewiththepassageofIme • Relevantbraincellsdieoff,orperhapstheconnecIons betweenmemoriesneedtobeconInuouslyrefreshed, andiftheyarenot,thentheconnecIonsgradually weaken InterferenceTheory • Learninginterfereswithotherlearning • InterferenceoccurswhencompeInginformaIon causesustoforget • ThepassageofImeiscorrelatedwithforgeEngbutit doesnotcauseforgeEng TwoTypesofMemoryInterference Whyyoucan’trememberthe nameofyourfriend’sgirlfriend ForgeEngcausedbythenumberofinterferingevents Baddeley&Hitch(1977) MemoryandAging • Episodicmemorydeclineswithage(Craik&Grady,2002), butsemanIcmemoryconInuestofuncIonwellintointo oldage(Mitchell,1989) • AparIcularlycostlyeffectofthelostofepisodicmemory inolderadultsistheimpairmentintheabilitytorecognize peopleand/orrecalltheirnames(Schweichetal.,1992) • AssociaIvedeficithypothesis:olderadultsareespecially deficientinmemorytasksthatrequirethemergingof differentaspectsofanepisodeintoacohesiveunit (Naveh-Benjamin,2000) Naveh-Benjaminetal.(2004) Howardetal.(1992) DisordersofMemory • Pathologicalmemorylosstypescanbegroupedintotwo maintypes: • DissociaIvedisorders:inwhichthedisrupIonsin memorylackaclearphysicalcause,andhenceappear tobepsychologicalinnature • Organicmemorydisorders:inwhichthephysicalcauses ofmemoryimpairmentareidenIfiable • Themostcommonkindsoforganicmemorydisordersare amnesiadisordersanddemenIas • Amnesiaisaseverelossofexplicitmemory(Robbins,2009) Retrogradeamnesia:isaninabilitytorememberthingsthat occurredbeforetheorganicdisorderortriggeringevent Anterogradeamnesia:isanongoinginabilitytoformnew memoriesagertheonsetoftheorganicdisorderorevent RetrogradeAmnesia • Retrogradeamnesia:lossofmemoryforeventsthat occurredbeforethetraumathatinducedthememory loss(Squire,1999) • Whenorifmemoriesdoreturn,theytypicallystart fromthemoredistantpastandthentheyprogressively returnuptotheImeofthetrauma • Buteventsthatoccurredrightbeforethetraumaare ogenneverrecalled AnterogradeAmnesia • Anterogradeamnesia:inabilitytoremembereventsthat occurageratraumaIcevent,butmemoryforeventsthat occurredbeforethetraumaaregenerallypreserved • Korsakoff’ssyndrome:commonlyseeninalcoholics, becauseitisaiributedtotheatrophyofbrainIssuethat resultsfrommalnutriIon,parIcularlythiamine(B1) deficiency • Korsakoff’spaIentsmaintainnormalfuncIoninginmany aspectsoflife,buttheyareunabletoformnewmemories foreventsthattakeplaceagertheonsetofthedisorder Amnesia • DisconnecIonsyndrome:paIentscanacquirenew informaIon,buttheyareunawarethatthelearning hastakenplace(Warrington&Weiskrantz,1982) • AmnesiapaIentsperformpoorlyonexplicitmemory tasks,butshownormalperformanceontasksinvolving implicitmemory(Warrington&Weiskrantz,1970) Graf&Schalter(1985) Graf&Schalter(1985) Alzheimer’sDisease • Alzheimer’sdisease:adiseaseofolderadultsthatcauses demenIaaswellasprogressivememoryloss • DemenIa:alossofintellectualfuncIonthatissevere enoughtoimpairaperson’severydaylife • PrevalenceofdemenIaisabout2%inpeoplethatare65 yearsofage,andisabout50%inpeoplethatareoverthe ageof85(Apostolova&Cummings,2008) • Atthispointroughlythree-quartersofamillionCanadians arelivingwithcogniIveimpairment,andthereareover 60,000newcasesofdemenIainCanadaeveryyear (Alzheimer’sSociety,2012) Alzheimer’sDisease • Alzheimer’sdiseaseisthemostcommonformof demenIa,itaccountsforabouttwo-thirdsofallcases (Brookmeyeretal.,2007) • Alzheimer’sdiseaseleadstoatrophyofthebrain; especiallyinthehippocampusandfrontaland temporalbrainregions(Jacketal.,2002) • ThebrainsofpeoplewithAlzheimer’sshowplagues andtanglesthatarenotfoundinnormalbrains NeuronaldegeneraIonassociatedwithAlzheimer’sdisease Alzheimer’sDisease • Plaques:denseproteindepositsthatarefoundoutside ofneuronsinthebrain(Mirochnicetal.,2009) • Tangles:foundinsidethecellbodyanddendritesof neurons,theyarefilamentpairsthatbecometwisted aroundeachother BrainscansshowthatAlzheimer’sdiseaseis associatedwithsignificantbrainatrophy PETscanstakenwhileperformingacogniIvetaskreveal muchlessbrainacIvityinpaIentswithAlzheimer’sdisease Alzheimer’sDisease • Diagnosedwhenmemoryisimpairedandthereisat leastoneotherareaofdysfuncIoninthedomainsof: language,motor,aienIon,execuIvefuncIon, personality,orobjectrecogniIon • Symptomsonsetgradually,andtheprogressionofthe diseaseisconInuousandirreversible • Thediseaseisdeterminedbyacomplexityoffactors, noneofwhichhavebeenconclusivelyidenIfied Alzheimer’sDisease • Earliestsignsinvolveanimpairmentofepisodic memory,withnobeiermemoryforemoIonalthan non-emoIonalmemory(Kensingeretal.,2002) • AsthediseaseprogressessemanIcmemorybeginsto declineaswell • Mostformsofnon-declaraIvememoryarespared unIltheendofthepaIentslifewhenAlzheimer’s diseasehasrunitscourse
