The neural bases of regularity learning [Elektronische Ressource] / vorgelegt von Christian Döller

Description

The Neural Bases of Regularity LearningDissertationzur Erlangung des Grades eines Doktors der Philosophieder Philosophischen Fakultaten der Universitat des Saarlandesvorgelegt von Dipl-Psych. Christian Dollergeboren am 10.12.1973 in WurzburgDekan:Prof. Dr. Rainer Krause, Universitat des SaarlandesBerichterstatter:Prof. Dr. Axel Mecklinger, Universitat des SaarlandesPD Dr. Hubert Zimmer, Universitat desTag der Disputation:14.02.2005I~Fur TanjaIIWe must suppose a very delicate adjustment whereby the circulation follows the needs ofthe cerebral activity. Blood very likely may rush to each region of the cortex according asit is most active, but of this we know nothing.William James, The Principles of Psychology (1890)Cognitive neuroscience can move forward with greater con denc e in the knowledge thatchanges in blood ow and oxygen levels do represent de nable alterations in neuronal ac-tivity.Marcus E. Raichle, Nature, 412 (2001)IIIAbstractThe existence of two separate learning and memory systems has been proposed in experi-mental psychology and cognitive neuroscience (Chapter 1), specialized for complementaryfunctions, namely (1) fast learning unique episodes ( rst system; Chapter 2) and (2) grad-ual learning regularities across multiple episodes (second 3). The presentthesis aimed at specifying the neural and cognitive bases of the second system.

Sujets

• Psychologie

Informations

• Publié par: universitat_des_saarlandes
• Publié le: 01 janvier 2005
• Nombre de lectures: 15
• Langue: English
• Poids de l'ouvrage: 9 Mo

Extrait

The

Neural

Bases

of

yRegularit

Dissertation

Learning

zurErlangungdesGradeseinesDoktorsderPhilosophie

der

PhilosophischenFakultatenderUniversitatdesSaarlandes

vorgelegtvonDipl-Psych.ChristianDoller

orengeb

amin10.12.1973

urzburgW

an:Dek

Prof.Dr.RainerKrause,UniversitatdesSaarlandes

terstatter:hBeric

Prof.Dr.AxelMecklinger,UniversitatdesSaarlandes

PDZimmer,ertHubDr.

TDisputation:derag

14.02.2005

atersitUniv

des

Saarlandes

I

urF

anjaT

I

I

♥

Wemustsupposeaverydelicateadjustmentwherebythecirculationfollowstheneedsof
thecerebralactivity.Bloodverylikelymayrushtoeachregionofthecortexaccordingas
itismostactive,butofthisweknownothing.

WilliamJames,ThePrinciplesofPsychology(1890)

Cognitiveneurosciencecanmoveforwardwithgreatercondenceintheknowledgethat
changesinbloodowandoxygenlevelsdorepresentdenablealterationsinneuronalac-
tivity.

III

MarcusE.Raichle,Nature,412(2001)

Abstract

Theexistenceoftwoseparatelearningandmemorysystemshasbeenproposedinexperi-
mentalpsychologyandcognitiveneuroscience(Chapter1),specializedforcomplementary
functions,namely(1)fastlearninguniqueepisodes(rstsystem;Chapter2)and(2)grad-
uallearningregularitiesacrossmultipleepisodes(secondsystem;Chapter3).Thepresent
thesisaimedatspecifyingtheneuralandcognitivebasesofthesecondsystem.Within
theframeworkofthisthesis,theterm‘regularitylearning’wasintroducedtodenethe
learningprocessassociatedwiththesecondsystem,namelytheextractionofregularities,
i.e.overlapping,invariantfeaturesofmultipleepisodes.
Theneuralandcognitiveprocessesunderlyingregularitylearningwereinvestigatedin
threeexperiments.Twobrainregionswereofmaininterest,thehippocampusandthe
prefrontalcortex,PFC(Chapter4).Functionalmagneticresonanceimaging(fMRI)was
usedasthemainmethod(Chapter5).Inallexperiments,volunteershadtolearnobject-
positionconjunctionsinseveralexperimentaltrialsandblocks.Thedesignoftheexper-
imentsincludedtwoconditions,acontext-specic(CS)andaninvariantlearning(IL)
condition(Chapter6).IntheCScondition,objectsandpositionswerevariablymapped
acrosstrials.Incontrast,intheILconditionpositions(Experiment1Aand3B)orobjects
(Experiment1B,2,and3A)wereheldconstantwithinblocks,enablingsubjectstoextract
regularitiesacrosstrials,i.e.invariantpositionsorobjectsinobject-positionconjunctions,
.elyectivrespInExperiment1A(Chapter7)andExperiment1B(Chapter8),performanceincreased
acrosstrialswithinblocksoftheILcondition,butnotintheCScondition.Inbothex-
periments,hippocampalactivitydecreasedasafunctionoflearningintheILcondition.
Conversely,thehippocampuswasactivatedcontinuouslyintheCScondition.Incontrast
toaright-lateralizedhippocampalactivationdecreaseduringlearningspatialregularities
(Experiment1A),learningobjectregularities(Experiment1B)wasassociatedwithade-
creaseofbilateralhippocampalactivity.Inbothexperiments,leftlateralprefrontaland
rightstriatalbrainregionsshowedanincreaseofactivityasafunctionoflearninginthe
ILcondition.InExperiment2(Chapter9),thecognitiveprocessesunderlyinglearning
objectregularitieswereinvestigatedinmoredetail.Insixbehavioralstudies,theinuence
ofobjectdistinctiveness(Experiment2A-2B),memoryloadandlearningduration(Exper-
iment2C-2E),andtheeectofsimultaneousobject-positionbindings(Experiment2F)on
learninginvariantobjectsinobject-positionconjunctionswasexamined.Thebehavioral

IV

V

dataindicatethattheincreaseofobjectdistinctivenessmainlyaectsoverallmemoryper-
formance,whereasmanipulationofthelearningdurationandthememoryloadaectsthe
learningprocess.Moreover,adissociationoftwolearningmechanismscouldbeobserved:
aprocessoperatingwithinlearningblocksandaprocessoperatingacrossblocks.Finally,
Experiment3(Chapter10)aimedatspecifyingwhetherseparablebrainregionsmediate
thesetwolearningmechanisms.IncontrasttoExperiment1Aand1B,trialswereblocked
byconditiontominimizetheprobabilitythatsubjectsbasedtheirjudgmentonacom-
monstrategyforbothconditions.Onabehaviorallevel,subjectsshowedaperformance
increasewithinandacrosslearningblocksinanobjectILcondition(Experiment3A)
andinaspatialILcondition(Experiment3B),butnotintherespectiveCSconditions.
Onaneurallevel,within-blocklearningwasassociatedwithalearning-relateddecrease
ofhippocampalandalearning-relatedincreaseofprefrontal-striatalactivityinbothex-
periments,bythisreplicatingtheresultsofExperiment1Aand1B.Incontrast,distinct
prefrontal-striatalregionswereselectivelyinvolvedinacross-blocklearning.
Tosummarize,onacognitivelevelregularitylearningwithintheframeworkofthepresent
thesiscanbecharacterizedbythefollowingcriteria:(1)theextractionofregularities
acrossinputpattern,(2)thegradualnatureoftheextractionprocess,(3)therobust
maintenanceofextractedregularitiesovertime,and(4)theaggregatedrepresentational
formatoftheextractedinformation.Furthermore,thedistinctionbetweenawithin-block
andanacross-blocklearningeectmightindicatethattheformereectisassociatedwith
aninstance-basedlearningprocess,whereasthelattereectmightreectarule-based
learningprocess,i.e.thetransferofknowledgeofinvariantfeaturestonewinstances.On
aneurallevel,regularitylearningwasassociatedwithadecreaseofhippocampalandan
increaseofprefrontal-striatalactivity.Thereducedlearning-relatedhippocampalactiva-
tionpresumablyreectslowerbindingrequirementsintheILcondition,sincevariable
objectscanbeboundtoinvariantpositions(Experiment1Aand3)orviceversa(Experi-
ment1B,2,and3).Furthermore,theimagingresultsofExperiment1Aand1Bsuggesta
domain-specichemisphericspecializationofthehippocampusduringregularitylearning,
reectinghippocampalsensitivitytoperceptualstimulusattributesofinvariantepisodic
features(bottom-upmechanism).Thelearning-relatedprefrontalmodulationseemstore-
ecttherequirementtoextractandmaintainregularitiesacrosstrialsandtheadjustment
ofobject-positionconjunctionsonthebasisoftheextractedknowledge,possiblymediated
byrule-likeprefrontalrepresentations(top-downmechanism).Finally,thestriatummight
encodetheincreasedpredictabilityofinvariantfeaturesasafunctionoflearningandpos-
siblyprovidesaninternalreinforcementsignaltothePFC.
Inconclusion,thepresentresultsprovidenewinsightsintotheneuralbasisofregularity
learningandpointtoatransitionoftherelativerolesofdistinctneuralsystemsdur-
ingthetime-courseofregularitylearning,i.e.learningisaccompaniedbyashiftfroma
hippocampaltoaprefrontal-striatalbrainsystem.

tstenCon

erviewOv0

troInIduction

ductiontroIn1

1

4

5

10TheoryII2FastLearningUniqueEpisodes:TheHippocampusandRelationalBind-
11ing2.1Introduction....................................12
2.2RelationalBindingandtheHippocampus:TheEichenbaumModelandthe
O’ReillyModel..................................14
2.2.1TheEichenbaumModel.........................14
2.2.2TheO’ReillyModel...........................15
2.3StudiesfromDierentAreasofBehavioralandCognitiveNeuroscience...16
2.3.1SingleCellRecordingsandLesionStudiesinAnimals........17
2.3.2AmnesiaResearch............................20
2.3.3ElectrophysiologicalStudiesinHumans................23
2.3.4ImagingStudies.............................26
2.4RepresentationofRegularitiesacrossMultipleEpisodes...........31
2.4.1AssumptionsoftheEichenbaumModel................31
2.4.2AssumptionsoftheO’ReillyModel...................32
2.4.3ConcludingRemarks...........................33

3GradualLearningRegularitiesacrossMultipleEpisodes:BasicPrinci-
plesandNeuralMechanisms35
3.1Introduction....................................36
3.2ReinforcementLearning.............................38
3.2.1BasicPrinciples..............................38
3.2.2NeuralMechanisms............................39

VI

CONTENTS

IVI

3.2.3Summary.................................46
3.3CategoryLearning................................46
3.3.1BasicPrinciples..............................46
3.3.2NeuralMechanisms............................47
3.3.3Summary.................................51
3.4ArticialGrammarLearning..........................51
3.4.1BasicPrinciples..............................51
3.4.2Rule-basedvsSimilarity-basedLearning................54
3.4.3NeuralMechanisms............................55
3.4.4Summary.................................57
3.5SequenceLearning................................57
3.5.1BasicPrinciples..............................57
3.5.2NeuralMechanisms............................62
3.5.3Summary.................................65

4NeuroanatomicalBasis:TheMedialTemporalLobeandthePrefrontal
66Cortex4.1MedialTemporalLobe..............................67
4.1.1MainStructures.............................67
4.1.2MainPathways..............................68
4.2PrefrontalCortex.................................69
4.2.1MainStructures.............................69
4.2.2MainPathways..............................70
4.3MedialTemporal-prefrontalInterconnections.................72

dsMethoIII

74

75NeuroimagingunctionalF55.1PrinciplesofMagneticResonanceImaging...................76
5.1.1NuclearSpinSystemsintheMagnet..................76
5.1.2ExcitationoftheSpinSystem......................77
5.1.3MagneticResonanceImaging......................80
5.1.4ImagingParametersandSequences...................81
5.2TheBOLDSignal................................83
5.2.1PhysicalBasis..............................83
5.2.2PhysiologicalBasis..