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The inhibition of automatic imitation: a meta-analysis and synthesis offMRI studiesDarda, Kohinoor Monish; Ramsey, Richard

Neuroimage

DOI:10.1016/j.neuroimage.2019.04.059

Published: 15/08/2019

Peer reviewed version

Cyswllt i'r cyhoeddiad / Link to publication

Dyfyniad o'r fersiwn a gyhoeddwyd / Citation for published version (APA):Darda, K. M., & Ramsey, R. (2019). The inhibition of automatic imitation: a meta-analysis andsynthesis of fMRI studies. Neuroimage, 197, 320-329.https://doi.org/10.1016/j.neuroimage.2019.04.059

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09. Oct. 2020

Journal:

Title:Theinhibitionofautomaticimitation:ameta-analysisandsynthesisoffMRI

studies

KohinoorM.DardaandRichardRamsey

WalesInstituteforCognitiveNeuroscience,SchoolofPsychology,BangorUniversity,

Bangor,Gwynedd,Wales,LL572AS,UnitedKingdom

Correspondingauthor:r.ramsey@bangor.ac.uk

Keywords:fMRI;imitation-inhibition;meta-analysis.

2

Abstract

Humanscopyotherpeoplewithouttheirconsciousawareness,abehaviourknownas

automaticimitation.Althoughautomaticimitationformsakeypartofdailysocial

interactions,wedonotcopyotherpeopleindiscriminately.Instead,wecontrolimitative

tendenciesbyprioritisingsomeactionsandinhibitingothers.Todate,neuroimaging

studiesinvestigatingthecontrolofautomaticimitationhaveproducedinconsistent

findings.Somestudiessuggestthatimitationcontrolreliesonadomain-specificneural

circuitrelatedtosocialcognition(thetheory-of-mindnetwork).Incontrast,other

studiesshowengagementofadomain-generalneuralcircuitthatisengagedduringa

diverserangeofcognitivecontroltasks(themultipledemandnetwork).Giventhe

inconsistencyofpriorfindings,inthecurrentpaperweavoidedproblemsassociated

withinterpretingindividualstudiesbyperformingameta-analysis.Todoso,weuseda

multi-levelkerneldensityanalysistoquantitativelyidentifyconsistentpatternsof

activationacrossfunctionalmagneticresonanceimagingstudiesinvestigatingthe

controlofimitation.Ourresultsshowclearandconsistentevidenceacrossstudiesthat

thecontrolofautomaticimitationisguidedbybrainregionsinthemultipledemand

networkincludingdorsolateralfrontoparietalcortex.Incontrast,therewasonlylimited

evidencethatregionsinthetheoryofmindnetworkwereengaged.Indeed,medial

prefrontalcortexshowednoconsistentengagementandrighttemporoparietaljunction

engagementmayreflectspatialratherthanimitativecontrol.Assuch,thecurrentmeta-

analysisreinforcestheroleofdomain-generalcontrolmechanismsandprovideslimited

evidenceinsupportoftheroleofdomain-specificprocessesinregulatingimitative

tendencies.Consequently,neurocognitivemodelsofimitationneedupdatingtoplace

moreemphasisondomain-generalcontrolmechanisms,aswellastoconsidermore

3

complexorganisationalstructuresofcontrol,whichmayinvolvecontributionsfrom

multiplecognitivesystems.

4

Introduction

Theinvoluntarytendencyofhumanbeingstoimitateothers’gestures,speechpatterns,

andpostures,isknownasautomaticimitation(Heyes,2011).Ithasbeensuggestedthat

suchautomaticimitativebehaviourfunctionsasa“socialglue”asitincreasespro-social

behaviour,positiverapport,feelingsofaffiliationandlikingbetweeninteracting

partners(Kavanagh&Winkielman,2016;vanBaaren,Janssen,Chartrand,&

Dijksterhuis,2009;Lakin&Chartrand,2003;Chartrand&Bargh,2009;vanBaaren,

Holland,Steenaert,VanKippenberg,2003).Giventheinfluenceofimitationon

strengtheningsocialbonds,researchershavestartedtoinvestigatethepsychological

andbiologicalmechanismsthatunderpinimitation.Forexample,overthelast20years,

researchershaveusedfunctionalmagneticresonanceimaging(fMRI)inordertobetter

understandtheneuralunderpinningsofthecontrolofautomaticimitativetendencies.

However,thesestudieshaveprovidedmixedfindingsregardingthecontributionsof

domain-generalordomain-specificneuralnetworksinimitationcontrol.Thecurrent

paper,therefore,meta-analysesfMRIstudiestodateonthecontrolofautomatic

imitationinordertoprovideacombinedquantitativeestimateoftheextantevidenceof

manyindividualstudies(Lipsey&Wilson,2001).

Inthelasttwodecades,automaticimitationhasbeenwidelystudiedwithan

attempttointerconnectdifferentdisciplineslikecognitivescience,socialpsychology,

evolutionarybiology,andcognitiveneuroscience(Prinz&Meltzoff,2002;Chartrand&

Bargh,1999;Byrne&Russon,1998).Thisconvergenceacrossmultipledisciplineshas

allowedforarangeofperspectivesonimitationtoemergeinwhichtheoryand

empiricaldatacanstrengtheneachother.Insocialpsychology,automaticimitationhas

beenstudiedinnaturalisticsocialinteractions(Chartrand&Lakin,2013).Alongwith

functioningasa“socialglue,”researchperformedinmorenaturalistsettingssuggests

5

thatimitationbehaviourisalsomoderatedbyothervariablesincluding,butnotlimited

to,personalityvariables,self-construal,goaltoaffiliateordisaffiliate,culturalandsocial

contexts,aswellasthesimilarity,familiarity,andstatusofthepersonbeingimitated

(Chartrand&Lakin,2013;Caspersetal.,2010;Duffy&Chartrand,2015).

Eventhoughautomaticimitationseemstobeanimportantbehaviourthat

facilitatessocialinteractions,wedonotalwayscopyothers’behaviours.Inmany

situations,imitationcanbemaladaptive,anditisessentialtocircumventthetendency

toautomaticallyimitate(Cross&Iacoboni,2014;Cross,Torrisi,Losin,&Iacoboni,2013;

vanSchie,vanWaterschoot,&Bekkering,2008;Newman-Norlund,vanSchie,van

Zuijlen,&Bekkering,2007).Thisneedtoregulateimitativetendenciesindicatesthe

existenceofaselectionmechanismthatinhibitsunwantedactions,andprioritises

alternatives(Brassetal.,2009).Thus,imitationcontrolcanbedividedintoatleasttwo

componentprocesses–actionrepresentationandactionselection.Weobservean

interactionpartnerandtheiractions(representation),andthenselecttheactionthat

needstobeexecuted(selection).

Incontrasttosocialpsychologyapproaches,researchersinthefieldofcognitive

psychologyandneurosciencehavegenerallyusedcomputer-basedreaction-time(RT)

measuresoftheinhibitionofautomaticimitation(Brassetal.,2000;Stürmeretal.,

2000).Oneofthemostcommonlyusedtasksinthisfieldconsistsinmakingfinger

movementswhilesimultaneouslyobservingacompatibleorincompatiblefinger

movement(Brassetal.,2000).Forexample,participantsmaybeaskedtomakeafinger

movementinresponsetoanimperativecuei.e.theyareinstructedtolifttheirindex

fingerwhentheyseeanumber‘1’onscreen,andtheirmiddlefingerwhentheyseea

number‘2.’Simultaneously,participantsalsoobserveatask-irrelevantindexormiddle

6

fingermovement,whichiscompatibleorincompatiblewiththeirownresponse.Other

variantsofthistaskincludehandopeningandclosingmovementsinsteadoffinger

movements(Pressetal.,2005;Wangetal.,2011)orpre-specifyingtheparticipant’s

responsebeforetheimperativecue(i.e.participantsareaskedtoalwayslifttheirindex

fingerwhentheyseeafingermovement;Brass,Bekkering&Prinz,2001;Heyesetal.,

2005).Inthesevariantsaswell,participantsobserveahandorfingermovementwhich

iscompatibleorincompatiblewiththeirownresponse.Irrespectiveofthetaskused,

greatercognitiveresourcesarerequiredwheninhibitingmovementsincompatibleto

one’sownresponses,thusleadingtogreaterRTs(Heyes,2011;Brass&Heyes,2005).

Thedifferencebetweentheincompatibleandcompatibleconditions(referredtoasthe

generalcompatibilityeffect)issaidtobeameasureofimitationcontrol(Heyesetal.,

2005;Heyes,2011).

Todate,anumberofneuroimagingstudieshaveinvestigatedtheneural

mechanismsofimitationcontrolusingRTparadigms.However,theevidence

demonstratingtheextenttowhichRTparadigmsofimitationcontrolengagedomain-

generalordomain-specificneuralnetworksismixed.Domain-specificprocesses

operateonparticulartypesofstimulioraspectsofcognition,whiledomain-general

processesoperateacrossarangeofstimuliandtasks(Barett,2012;Spunt&Adolphs,

2017).Oneoftheprevailingtheoriesofautomaticimitationproposesthatimitation

controlreliesonadomain-specificneuralcircuitrelatedtosocialcognition(Brassetal.,

2009).This“specialist”theoryhasgainedtractionwithevidencefrompatientand

neuroimagingdatapointingtotheengagementoftwokeycandidateregions–the

anteriormedialprefrontalcortex(mPFC)andtherighttemporoparietaljunction(rTPJ)

(Brass&Heyes,2005;Brassetal.,2009).Forexample,mPFCandrTPJhavebeen

7

engagedinhumanbrainimaginginvestigationsofimitationinhibition(Brassetal.,

2001;2005;2009;Spengleretal.,2009;Wangetal.,2011).Brassandcolleaguesfurther

proposedadissociationofrolesforthemPFCandrTPJduringimitationcontrol-the

rTPJdistinguishesbetweenself-andother-generatedactions,andthemPFCenforces

theself-generatedactionwhenfacedwithconflictfromanactionrepresentation

generatedbyanotheragent(Brassetal.,2009).Inaddition,patientswithfrontallobe

lesionsshowdisruptedimitationinhibitionbehaviour(Brassetal.,2003;Spengleretal.,

2010)andanincreasedtendencytoautomaticallyimitateevenwhentheyareclearly

instructedtonotdoso(Lhermitteetal.,1986).Moreevidencefortheinvolvementof

rTPJcomesfromneuro-stimulationstudies:inhibitingtheactivityintherTPJby

transcranialmagneticstimulation(TMS)interferedwithimitativeresponsesimpairing

imitationinhibition(Hogeveenetal.,2014;Sowden&Catmur,2015).Irrespectiveofthe

methodused,itisworthnotingthat,todate,therehaveonlybeenasmallnumberof

studiesimplicatingmPFCandrTPJinthecontrolofimitation.Moreover,thesestudies

haveusedrelativelysmallsamplesizesbetween10and25participantsandtherehave

beenfew,ifany,directreplications.Therefore,thesumtotalofevidenceformPFCand

rTPJengagementduringimitationcontrolissuggestiveratherthancompelling.

Alongwithimitativecontrol,neuroimagingfindingssuggestmPFCandrTPJare

alsoengagedinavarietyofsocio-cognitivetasksthatareassociatedwiththeoryof

mind,includingdistinguishingbetweenselffromother,perspectivetaking,aswellas

attributingbeliefs,desiresandattitudestoothers(ToM;Gallagheretal.,2000;Amodio

&Frith,2006;Ruby&Decety,2001;Aichhornetal.,2006;Decetyetal.,2002;

Santiestebanetal.,2012;Brassetal.,2009;Spengleretal.,2010).Basedonthese

findings,self-othercontrolprocesseshavethusbeenproposedasacandidate

8

mechanismforarangeofsocio-cognitivefunctions.Forexample,itisimportantto

inhibitone’sownperspectiveormentalstateandenhancethatoftheotherwhen

empathisingwithothers,takingtheirperspective,orengagingasuccessfultheory-of-

mind(deGuzmanetal.,2016;Sowden&Shah,2014).Further,atypicalself-other

controlhasbeenlinkedtodisorderscharacterisedbysocialdysfunctionincluding

autismandschizophrenia(CookandBird ,2012;Ferrietal.,2012).Overall,this

evidencesuggeststhatinimitationcontrol,itiscrucialtoinhibittherepresentationof

theother’saction,andenforceyourown,andthismechanismisguidedbyadomain-

specificneuralcircuituniquetosocialcognition(Brassetal.,2009).

Incontrasttothis“specialist”viewofimitationcontrol,however,“generalist”

theoriesofimitationsuggestthattheinhibitionofautomaticimitationdoesnotdiffer

fromanyotherpre-potenttendenciesorgeneralcognitivefunctions(Heyes,2011;

Cooperetal.,2013).MultiplecognitivecontroltasksliketheFlanker,Stroop,andSimon

tasks,whichrequiretheinhibitionofautomaticoverlearnedresponsetendencies,have

beenfoundtoengageadomain-generalcontrolnetworkidentifiedinthedorsolateral

fronto-parietalcortices(Aronetal.,2014;Bungeetal.,2002;Hazeltineetal.,2007;Nee

etal.,2007;Wageretal.,2005).Thisnetworkisalsocalledthemultipledemand(MD)

networkasitisengagedacrossadiversityofmentaloperations(Duncanetal.,2010).

Acrossstudiesthatinvestigateimitationinhibition,somehavefoundengagementofthe

mPFCandrTPJ(Brassetal.,2001;2005;2009;Spengleretal.,2009),whereasothers

showengagementoftheMDnetwork(Bien,Roebroeck,Goebel,&Sack,2009;

Crescentini,Mengotti,Grecucci,&Rumiati,2011;Cross&Iacoboni,2013;Mengotti,

Corradi-Dell’Acqua,&Rumiati,2012;Marshetal.,2016).However,mostpreviousfMRI

studieshavebeenlimitedbylowstatisticalpowerandsmallsamplesizes.More

9

recently,amulti-experimentstudyusinglargersamplesizes(N=28,N=50)anda

functionalregionofinterest(fROI)approachthatbolstersstatisticalpowerand

functionalsensitivityhasshownthatimitationcontrolengagesonlytheMDnetwork,

andnotmPFCorrTPJ(Darda,Butler&Ramsey,2018).Indeed,evenwithanapriori

poweranalysisensuring80%powertodetectmediumeffectsizes,Dardaand

colleagues(2018)didnotevenfindadirectionaltrendtosuggestthattheToMnetwork

wasdirectlyengagedduringimitationcontrol.

Asmentionedbefore,imitationcontrolcanbedividedintoatleasttwo

componentprocesses–actionrepresentationandactionselection.Theabovereviewof

literaturesuggeststwopossibleneuralmechanismsasbeingkeytoactionselection

duringimitationcontrol.Ononehand,duringimitationcontrol,theneural

representationgeneratedbytheobservedperson’sactionisinhibited,andtheself-

generatedactionisselectedandenforcedandthisselectionmechanismengagesa

domain-specificneuralnetworki.e.themPFCandrTPJ.Ontheotherhand,theselection

mechanismmaybeguidedbyadomain-generalneuralnetworki.e.theMDnetwork.In

bothpossiblemechanisms,theinputisthesamei.e.theobservedpersonandaction

mayengagedomain-specificsocio-perceptualneuralcircuits.However,thedifference

liesintheselectionorcontrolmechanismthatunderliestheinhibitionofautomatic

imitativetendencieswhichfinallyleadstoconsequentbehaviour(seegraphical

representationinFigure1).

Thequestionofinterestforthecurrentmeta-analysis,therefore,liesatthe

selectionstageofimitationcontrolwiththeevidencetodateforengagementofdomain-

specificanddomain-generalneuralnetworksbeinginconsistent.Eventhoughthemost

statisticallypowerfulfMRIstudytodateonlyshowstheengagementoftheMDnetwork

10

(Dardaetal.,2018),theinterpretationofindividualstudiesremainslimitedinscopefor

severalreasons.First,manysinglestudiesarelikelytobeunderpoweredleadingto

missedorspuriousresults(Buttonetal.,2013).Second,empiricalworkinvolvesdesign

choicesthatstronglyinfluenceresults,makingithardertogeneraliseeffectsacross

analysispipelinesanddifferingexperimentalprocedures(Carp,2012).Giventhe

inconsistencyofpriorfindingsandtheabsenceofaquantitativesynthesisofevidence,

takingameta-analyticalapproachtofurtherinvestigatetheneuralbasisofimitation

hasmanybenefits(Cumming,2014).Assuch,bymeansofameta-analysis,thecurrent

paperenablesthedetectionofconsistentpatternsofactivationacrossstudies.

Inordertoquantifytheconsistencyandspecificityofregionalactivationfor

imitationcontrolacrossstudies,weperformedamulti-levelkerneldensityanalysis

(MKDA;seeMethodsandMaterialsfordetails).WeincludedallfMRIstudies(N=12)

investigatingimitationcontrolusingtheRTmeasureofimitationinhibition(seeTable

1).Ourprimarymeasureaimedtoquantifytheconsistencyofregionengagement

acrossstudieswithparticularfocusontheengagementoftheToMnetworkandtheMD

network.Thedependentvariablewasthebloodoxygenleveldependent(BOLD)

responsemeasuredintheincludedfMRIstudies.Giventhepriormixedfindingsacross

studies,thismeta-analysisaimedtoquantifytheextenttowhichToM,MDorboth

neuralnetworksmaybeengagedwhenduringtheinhibitionofautomaticimitation.

Wealsorantwomoreexploratoryanalyses,whichwerebasedonasmallsubset

ofthetotalstudies.Themostcommonmeasureofimitationinhibition,thegeneral

compatibilityeffect,alsoincludesaspatialcomponent(Heyes,2011).Inorderto

measureimitativecompatibilitymorespecifically,therefore,imitativeandspatial

effectsneedtobedissociated(Gowenetal.,2016;Boyeretal.,2012;Catmur&Heyes,

11

2011).However,onlyafewfMRIstudieshavemeasuredtheimitativecompatibility

effectindependentofthespatialcomponent(Dardaetal.,2018;Marshetal.,2016;

Crossetal.,2013).ThismakesitdifficulttointerprettherolesoftheToM(mPFCand

rTPJ)andMDnetworksinimitationcontrol–theirengagementcouldreflectbothsocial

(imitative)and/ornon-social(spatial)control.Indeed,therTPJhasbeenpreviously

associatedwithorientingtobothsocialandnon-socialstimuli(Corbettaetal.,2008;

Thieletal.,2004).Thus,giventhatonlyafewstudieshavedissociatedbetween

imitative(N=3)andspatialcompatibility(N=4)effects,wealsorantwofurther

exploratoryMKDAsinordertoquantifyconsistencyofpatternsacrossstudiesforboth

imitativeandspatialcompatibilityeffects.Indeed,giventhelownumberofstudies

includedinthesecondaryanalyses,theseresultsprovideonlysuggestive,andnot

compelling,evidenceregardingtheroleoftheMDandToMnetworksinimitativeand

spatialcontrol.

MethodsandMaterials

Literaturesearchanddatacollection

Inthecurrentpaper,wefollowrecentguidelinesputforwardformeta-

analysingneuroimagingstudies(Mulleretal.,2018).FMRIstudiesexploringthe

inhibitionofautomaticimitativetendenciesweresearchedforontheonlinedatabase

PubMed,aswellasthearticlesearchengineGoogleScholar.Combinationsofkeywords

including‘imitationinhibition,’‘fMRI,’‘imitation,’‘automaticimitation,’and‘imitation

control’wereusedtoidentifyrelevantliterature(priortoJanuary2019).Atotalof15

studieswerefound.Werejectedstudiesiftheprimarymethodofinvestigationwasnot

fMRI,ifthestudydidnotreportresultsinstereotacticcoordinatespace(either

MontrealneurologicalInstitute(MNI)orTalaraichcoordinates)(N=1;Bienetal.,2009),

12

ifreportedresultswerebasedonregion-of-interest(ROI)analyses,andthestudydid

notreportwhole-brainanalysiscoordinateseitherinthemainarticleorin

supplementarymaterials(orwecouldnotobtainthemfromtheauthors)(N=1;Brasset

al.,2009),andifthestudyinvolvedchildrenoratypicalpopulations(andthe

coordinatesforcontrolswerenotreportedseparately)(N=1;Spengler,Bird,&Brass,

2010).

Awidevarietyofcontrastsareusedinstudiesthatinvestigatetheinhibitionof

automaticimitation.However,inordertominimiseheterogeneity,studiesthatuseda

paradigmthatwasnotbasedonorwasnotconceptuallysimilartotheBrassetal.

(2000)paradigmformeasuringinhibitionofautomaticimitationwerealsoexcluded.

Thus,12studieswithatotalof300participantswereincludedinthemeta-analysis(see

Table1).

Eventhoughourmainanalysiswasonthegeneralcompatibilityeffect,wealso

rantwoseparatemeta-analysesforspatialandimitativecompatibility.Table2

summarisesthecontrastsusedinthecurrentmeta-analysisforgeneral,spatial,and

imitativecompatibilityeffects.Atotalof13contrastsacross12studieswith142foci

wereusedforgeneralcompatibility,4contrastsacross4studieswith42fociwereused

forspatialcompatibility,andatotalof3contrastsacross3studieswith20fociwere

usedforimitativecompatibility.

Dataanalysis

AllanalysesinthecurrentpaperwereperformedinMatlabR2015b

(Mathworks,Naticks,MA)usingtheMKDAtoolboxdevelopedbyWageretal.,2007;

http://wagerlab.colorado.edu).MKDAisananalysistechniquethatusesarandom

effectsmodeltoassessconvergenceacrossstudies.Thisallowsforassessing

convergenceacrossstudiesasopposedtobetweenindividualfoci(asimplementedin

13

classicalmeta-analysistechniquesthatusefixedeffectsanalyses).Thus,resultsarenot

biasedbyasmallnumberofindividualstudies.Further,eachcontrastisweightedby

thesamplesizeandstudyquality(i.e.whetherthestudyusedfixedorrandomeffects

model;Wageretal.,2007;KoberandWager,2010).

MKDAwasperformedonallthreecompatibilitytypesseparately.Before

performingtheanalyses,weextractedthefollowinginformationfromeachstudyand

includeditinourdatabase:authors,yearofpublication,samplesize,taskcontrasts,

fixedorrandomeffectsmodel,andMNIorTalaraichco-ordinates.Co-ordinates

reportedinTalairachspacewereconvertedtoMNIstereotacticspaceusingLancaster

transformation(tal2icbmtransform;Lancasteretal.,2007).Peakcoordinatesfromeach

contrastmapwerethenconvolvedwitha10mmsphericalkernelinordertocreatea

contrastindicatormap(CIM).Theresultingvoxelswithin10mmofthepeakwere

deemed“significant”andgivenavalueofone;othervoxelsweregivenavalueofzero

whichindicatednosignificanteffect.Adensitymapwasthencreatedbyaveragingthe

indicatormaps,weightedbysamplesize,andwhetherthestudyusedafixedorrandom

effectsmodel.Morespecifically,asrecommendedbyWagerandcolleagues(Wager,

Lindquist,&Kaplan,2007),thisdensitymapwasweightedbythesquarerootofthe

samplesizeofthestudy,andthenmultipliedbyanadjustmentfactorof1forrandom

effectsanalysis,and.75forafixedeffectsanalysis.

EachvoxelofthedensitymapwasgivenadensitystatisticP.Pstandsforthe

proportionofcontrastsincludedintheanalysisthatshowactivitywithin10mmofthe

voxel.AMonteCarlosimulation(with5000iterations)wasthencarriedoutinorderto

identifyvoxelsthathadaP-statisticthatwashigherthanthefrequencypredictedby

chance.Thiswastestedagainstthenullhypothesisthatactivatedregionsinthe

resultingpairwisecontrastmaps(fromthe5000iterations)wererandomlydistributed

14

acrossthebrain.Totestforthesignificanceoftheclustersize,asimilarprocedurewas

used.Thisallowedfortheidentificationofathresholdforclustersizeatwhichaspecific

numberofvoxelsneededtobeactivatedcontiguouslysothattheclustercouldbe

deemedsignificant.

Inordertomaximisesensitivityintestingourhypotheses,wereportresults

usingtwothresholdingtechniques.Onethresholdingtechniqueisbasedonheightand

theotherisbasedonclustersize.FortheweightedP-statistic(height-basedthreshold),

thefamilywiseerror(FWE)correctedthresholdistheproportionofstudieswhich

yieldedactivitywithin10mmofavoxelthatshowedahigherP-statisticthanthe

maximumP-statisticacross95%oftheMonteCarlomaps.Fortheclustersize

threshold,theFWEcorrectedthresholdisthecontiguousvoxelsobservedattwo

differentthresholds(p<.001andp<.01)whoseclustersizeismorethantheextentof

clustersfoundacross95%oftheMonteCarlomaps.Weusetwocluster-based

thresholdsinordertoalsodetectregionsthatshowalowerresponseinmagnitudeover

alargerclustersizebothatmorestringent(p<.001)andlessstringent(p<.01)

thresholds.Voxelsthatexceedtheheight-basedthresholdinouranalysisappearonthe

resultingmapsinFigure2inyellow,andthosethatexceedtheclusterextent-based

thresholdappearinorange(p<.001)andred(p<.01).

Intheresultingtable(Table3),peakactivationfocithatpasstheheight-based

thresholdarereported.Ifactivationsdonotpasstheheight-basedthreshold,fociofthe

cluster-extent-basedthresholdingarereported.Thenumberofvoxelsineachcluster

thatsurvivedheight-basedand/orextent-basedthresholdingisalsoreported.Resulting

coordinateswerelocalisedusingtheSPMAnatomyToolbox(Eickhoffetal.,2005).The

databaseofco-ordinates,andcodeusedtoperformthemeta-analysisareavailable

online(https://osf.io/dbuwr/).

15

Results

Forthegeneralcompatibilityeffect,across13contrastsfrom12studies,

consistentactivationwasfoundinrightinferiorparietallobule,rightsupramarginal

gyrus,rightsuperiortemporalgyrus,andrighttemporo-parietaljunction(seeTable3;

Figure2A).Theseclusterssurvivedbothheight-basedandthemorestringentextent-

basedthresholding(p<.001).Activationwasalsofoundinrightsuperiorfrontalgyrus,

andrightmiddlefrontalgyrus,whichsurvivedbothheightandthelessstringentextent-

basedthresholding(p<.01).Activationintheleftandrightinsulasurvivedthemore

stringentextent-basedthreshold(p<.001),butnottheheight-basedthreshold.

ActivationintherightIFGsurvivedthelessstringentextent-basedthreshold(p<.01)

butnottheheight-basedthreshold.

WerantwofurtherMKDAsseparatelyforspatialandimitativecompatibility.

Forspatialcompatibility,across4contrastsfrom4studies,wefoundconsistent

activationthatwithstoodtheheight-basedthresholdingintheleftIPLandtherightSFG

(seeTable3;Figure2B).Noregionswithstoodcluster-basedthresholding.Forimitative

compatibility,across3contrastsfrom3studies,wefoundconsistentactivationinthe

leftIPLthatsurvivedheight-based(seeTable3;Figure2C).Activationwasalsofoundin

therightIPL,whichwithstoodheight-basedaswellasthelessstringentextent-based

thresholding(p<.01).

Thesedensitymapsshowingregionsthatwithstoodbothheightand/orcluster-

extentthresholdingforeachcompatibilitytypewerethenoverlaidwiththeToMand

MDnetworkmasksseparately.TheToMnetworkmaskconsistedoffourparcels

includingthedorsal,medial,andventralmedialprefrontalcortex(DMPFC,MMPFC,

VMPFC),andtherighttemporo-parietaljunction(rTPJ),whichhavepreviouslybeen

implicatedinmentalisingortheory-of-mind(Dufouretal.,2013).FortheMDnetwork

16

mask,16parcelswereusedwhichincludedareasinbilateralsuperiorandinferior

parietallobules(SPL,IPL),intraparietalsulcus(IPS),inferiorandmiddlefrontalgyrus

(IFG,MFG),precentralgyrus(PrecG),insula(Ins),andthesupplementarymotorarea

(SMA)(availableat:https://evlab.mit.edu/funcloc/download-parcels).Overlayofthe

densitymapswiththeToMandMDnetworkmasksallowedforidentificationofoverlap

betweenregionsthatwereconsistentlyactivatedintheMKDAandtheToMandMD

networks(Figure3).Forallcompatibilitytypes(general,imitativeandspatial),all

regionsthatpassedheightorextent-basedthresholdingoverlappedwithregionsinthe

MDnetwork(Figure3A).Additionally,onecluster,whichshowedconsistentactivation

forgeneralcompatibility,alsooverlappedwiththerightTPJintheToMnetwork(Figure

3B).TherewasnooverlapwiththemPFCnodeoftheToMnetworkforany

compatibilitytype.

InordertobreakdowntheroleoftherightTPJingeneralcompatibility,we

performedafurther,moreexploratoryanalysis.Wecomparedpeakcoordinatesfrom

priorstudieswitharightTPJmask,whichhasbeenpreviouslyimplicatedintheory-of-

mind(Dufouretal.,2013).Todoso,theToMnetworkmaskforrTPJwasoverlaidwith

thecontrastindicatormapsofallstudiesusedforimitative(N=3)andspatial(N=4)

compatibility.Thecontrastindicatormapsinclude10mmsphericalkernelsaround

peakcoordinatesofeachcontrast.Thisallowscoordinatesfrompriorimitativeand

spatialcompatibilitycontraststobedisplayedwithoutanythresholdingrestrictions

andoverlaidwiththerTPJnodeoftheToMnetwork.Figure4showsoverlapbetween

contrastindicatormapsforgeneralcompatibilityandspatialcompatibilitywiththe

rightTPJnodeoftheToMnetworkmask.Bycontrast,thereisnooverlapbetween

contrastindicatormapsforimitativecompatibilityandthesamerightTPJmask.

17

Discussion

Inthecurrentpaper,weperformedameta-analysisoffMRIstudiesinordertoquantify

theconsistencyandspecificityofregionalactivationduringtheinhibitionofautomatic

imitation.Ourresultssupporteda“generalist”viewofimitationcontrol–wefound

clearengagementofdorsolateralfrontoparietalcorticeswhenobservinganactionthat

conflictedwithacurrentmotorintention.Theseregionsoverlappedwithregions

associatedwiththeMDnetwork.Wefoundlessevidencefora“specialist”viewof

imitationcontrol,whichreliesontheToMnetwork.Indeed,therewasnoengagementof

mPFCacrossstudiesandtherewasnoclearevidenceregardingtheengagementofrTPJ;

therewasonlysuggestiveevidencethatitmayreflectspatialratherthansocialcontrol.

Thus,ourresultsprovideunambiguoussupportfortheengagementofadomain-

generalneuralnetworkduringthecontrolofimitation,andonlylimitedevidencefor

theengagementofadomain-specificneuralnetworkthatistiedtosocialcognition.

Studiesinvestigatingtheneuralcorrelatesofimitationcontrolhavetodate

shownmixedevidencefortheengagementofdomain-generalanddomain-specific

neuralnetworksinimitationinhibition.Whilesomestudieshavefoundengagementof

themPFCandrTPJ(Brassetal.,2001;2005;2009;Spengleretal.,2009),othersshow

engagementoftheMDnetwork(Bien,Roebroeck,Goebel,&Sack,2009;Marshetal.,

2016;Dardaetal.,2018).ThecurrentMKDAdemonstratedthatbrainregionsinthe

multipledemandnetworkarereliablyandconsistentlyengagedacrossstudiesthat

investigateimitationinhibitionusingthegeneralcompatibilityeffect.Brainregionsin

theMDnetworkarealsoengagedforimitative(bilateralIPL)andspatialcompatibility

effects(leftIPL,rightSFG).Thus,ourfindingssuggestthatbrainregionsthatare

engagedacrossarangeofcognitivecontroltasksarealsoreliablyengagedwhen

18

controllingtheautomatictendencytoimitateothers,asmeasuredbygeneraland

imitativecompatibilityeffects.

Evidencesupportingtheengagementofadomain-specificneuralcircuitthatis

centraltosocialcognitionandincludesmPFCandrTPJwaslessconsistentinthe

currentmeta-analysis.Brassetal.(2009)proposedthattherTPJwasinvolvedin

distinguishingbetweenself-andother-generatedactions,whereasthemPFCwas

engagedwhenenforcingthecorrectaction.However,thecurrentMKDAdidnotfind

anyevidenceofanteriormPFCengagementforeithergeneral,spatial,orimitative

compatibilityeffects.AnabsenceofmPFCengagementforimitationcontrolacross

studiesisthusinconsistentwiththehypothesisthataspecificneuralsystemrelatedto

socialcognitionisalsoengagedduringtheinhibitionofautomaticimitation(Brassetal.,

2009).

IncontrasttotheresultsreportedinmPFC,acrossstudiesinvestigating

imitationinhibitionasmeasuredbythegeneralcompatibilityeffect,thecurrentmeta-

analysisfoundengagementofrTPJ.However,itisdifficulttointerprettheroleofrTPJin

imitationcontrolforatleasttworeasons.First,thegeneralcompatibilityeffectisa

productofbothspatialandimitativeeffects,whichmakesithardtointerpretina

straightforwardmanner.Second,rTPJisinvolvedinbothsocialandnon-social

processes,whichmakesitafunctionallyheterogenousregion(Corbettaetal.,2008;

Kralletal.,2015,2016;Lee&McCarthy,2016;Schuwerketal.,2017).

Further,inthecurrentmeta-analysis,across12studies,wefindengagementof

rTPJforthegeneralcompatibilityeffect.However,itisimportanttodistinguish

betweenasynthesisofevidencebasedonadescriptiveapproach,andaquantitative

meta-analysis(Gigerenzer,2018).Todate,14fMRIstudieshaveinvestigatedimitation

controlbymeasuringthegeneralcompatibilityeffect(weexcludedBienetal.,2009and

19

Brassetal.,2009inthemeta-analysis,seeMethods).Outofthe14studies,only4

studiesreporttheengagementofrTPJforthegeneralcompatibilityeffect(seeDardaet

al.,2018,Table1formoredetails).Thus,wefindthatonly28.6%offMRIstudieson

imitationcontroltodate(4/14)showanyevidenceinsupportofaroleofrTPJin

imitationcontrol,andthesestudiesdonotdissociatebetweenspatialandimitative

effects.

InthelargestandmostsensitivefMRIstudyofimitationinhibitiontodate,

Dardaandcolleagues(2018)showednoengagementofrTPJfortheimitative

compatibilityeffect,butengagementofrTPJforgeneralandspatialcompatibility

effects.Similarly,inthecurrentmeta-analysis,whenweexploredtheunthresholded

spatialandimitativecompatibilityeffectmapsseparately,therewaspartialoverlap

betweenthespatialcompatibilityeffectandrTPJ,butnooverlapbetweentheimitative

compatibilityeffectandrTPJ.GiventhatthesmallnumberoffMRIstudiesinvestigating

spatialandimitativecompatibilityeffectsseparately(N=4andN=3,respectively),the

currentfindingsneedtobeinterpretedwithcaution.However,whentakentogether

withpriorfindings,theresultsprovideconsistentlylimitedevidencefortheunivariate

engagementofrTPJinthecontrolofimitativetendencies.Incontrast,currentfMRI

findingsprovidemoreevidencethatrTPJisinvolvedinresolvingspatialconflict,which

isinkeepingwithpatientwork(Vallar&Perani,1987;Valleretal.,1993),aswellas

evidenceusingspatialcueingtaskslikethePosnerparadigm(Posner&Cohen,1984;

Thieletal.,2004;Corbettaetal.,2008).MorerecentworkalsosuggeststhatrTPJmay

playamoredomain-generalroleintheprocessofcontextualupdating,actingon

changingexpectationsafterunexpectedevents(Geng&Vossel,2013;Mengottietal.,

2017).Assumingthatonincompatibletrialsexpectationsareviolated,rTPJmayplaya

moregeneralisedroleofcontextupdatinginimitationandspatialcontrol.However,

20

irrespectiveofwhetheritplaysadomain-specificordomain-generalrole,inthecurrent

meta-analysis,wefindlimitedevidencefortheunivariateengagementofrTPJinthe

controlofautomaticimitativetendencies.

Limitationsandalternativeinterpretations

Beforemovingontothewidertheoreticalimplicationsoftheseresults,wefirst

acknowledgepossiblelimitationstothecurrentmeta-analyticalapproach.Thecurrent

meta-analysisdidnotincludeworkbyBrassandcolleagues(2009),whichimplicated

rTPJandmPFCinimitationcontrol,duetothewhole-braindatabeingunavailable.

Nonetheless,asmentionedbefore,only28.6%(4/14)offMRIstudies,whichhave

investigatedimitationcontrol,foundengagementofmPFCandrTPJ,andtheyallhad

smallsamplesizes(between10and20participants).Itis,therefore,unlikelythatthe

inclusionofanadditionalstudywitharelativelysmallsamplesize(Brassetal.,2009)

wouldchangetheresultsofthemeta-analysis,giventhattheyareweightedbysample

size.

AfurtherconsiderationistherelativesizeoftheMDandToMnetworksthatwe

usedinouranalyses.GiventhattheMDnetworkspansamuchlargerareathantheToM

network,ouranalysismaybebiasedtowardfindingresultsintheMDnetworkoverthe

ToMnetwork.Althoughthisistrueinarelativesense,wedonotfeelthatithindersour

interpretationoftheresultsintheToMnetworkforseveralreasons.First,regionsof

interestintheToMnetworkwerenotparticularlysmallareas.ThemPFCregions

includedseveralportionsofthedorsal,middle,andventralmPFC,andtherTPJcovered

arelativelylargeareaofcortex.Second,bothnetworksweredefinedaccuratelybased

onpriorwork,whichusedlargesamplesofparticipants.Thus,eventhoughToMareas

werecomparativelysmallerthantheMDnetwork,theystillcoveredaswathofcortexin

21

regionsfunctionallyandpreciselydefinedastheToMnetwork.Consequently,wefeel

confidentthathadtheseregionsbeenconsistentlyengagedacrossstudies,wewould

havebeenabletodetectthem.Third,evenifweonlyuseCIMsacrossthewholebrain,

whichreportactivationpeaksfrompriorstudies,thusavoidingissueswith

thresholdingorchoiceofmasks,westilldonotfindevidenceforengagementnearrTPJ

andmPFCfortheimitativecompatibilityeffect(Figure4).

Anadditionalpossibilitytoconsideristhatthedifferencebetweentheresults

intermsofdomain-specificanddomain-generalnetworkengagementcouldbedueto

thedifferencesinstimuliusedinthestudiesincludedinthemeta-analysis.However,

thetasksareallconceptually,visuallyandcognitivelysimilartoeachotherwithonly

minordifferencesacrossallstudies.Forexample,inDardaetal.,(2018;Exp1and

Exp2),thestimuliconsistofindexandmiddlefingermovements,whereasinWangetal.

(2011),handopeningandclosingmovementsareused.Moreover,arecentmeta-

analysisalsoshowedthatbehaviouralperformanceisconsistentacrossarangeof

studiesthatcoverarangeofminormethodologicaldifferences(Craccoetal.,2018).

Giventhelackofsubstantialdifferencesbetweenthestudiesandtheconsistentpattern

ofbehaviouraldata,itseemsunlikelythatsmalldifferencescouldberesponsiblefor

theseeffects.

Finally,weacknowledgethatfMRIisonlyoneformofmeasurement,anditis

importanttoconsiderhowthesefindingsmeshwithresultsfromotherneuroscience

techniques.Forinstance,neurostimulationstudieshaveimplicatedrTPJinimitation

control(Santiestebanetal.,2015;Bardietal.,2017).Usingrepetitivetranscranial

magneticstimulation(TMS),dampeningofactivityintherTPJinterferedwithimitative,

butnotspatialresponses(Hogeveenetal.,2014;Sowden&Catmur,2015),whereas

excitatorystimulationoftherTPJbyanodaltranscranialdirectcurrentstimulation

22

(tDCS)causedincreasedperformanceontheimitationtask(Santiestebanetal.,2012).

Further,inpatientswithlesionsinthetemporoparietaljunctionarea,imitation

inhibitiondeficitshavebeenfoundtocorrelatewithdeficitsinvisualandcognitive

perspectivetakingtasks,furthersupportingtheroleofrTPJinimitationcontrol

(Spengleretal.,2010).Thus,thereseemstobeadiscrepancybetweenneurostimulation

andpatientstudies,andresultsfromthecurrentmeta-analysisoffMRIstudies.The

evidencefromneurostimulationandpatientstudiesfortheengagementofrTPJin

imitationcontrolis,however,limitedtoafewstudieswithsmallsamplesizes.Under

anyyardstick,therefore,thesumtotalofevidencefromneurostimulationandpatient

studiescanonlybejudgedtobesuggestiveatpresent.Itisbasedonafewstudieswith

smallsamplesizesthatlackformalpoweranalysesandreplications.Therefore,for

moreconfirmatoryevidence,futureinvestigationswithpre-registeredandadequately

poweredreplicationsareessential(Munafoetal.,2017;Zwaanetal.,2018;Nelsonetal.,

2018).Inaddition,itisalsopossiblethattheroleofrTPJinimitationcontrolcannotbe

capturedbyunivariatemeasurementsandamorecomplexneuralorganisationisat

playduringimitationcontrol.

Theoreticalimplications

ThelackofconsistentactivationinmPFCinthecurrentmeta-analysisanda

difficultyininterpretingtheroleofrTPJhaveimplicationsfor“specialist”theoriesof

imitation.“Specialist”theoriessuggestthatbasedonadedicatedneuralcircuitforsocial

cognition,self-othercontroliscrucialfortheregulationofimitation,empathy,autism,

andtheory-of-mind(Brassetal.,2009;deGuzmanetal.,2016;Sowden&Shah,2014).

However,morerecentbehaviouralevidencesuggeststhatimitationmaynotvaryasa

functionofautistic-liketraitsorempathy,thusquestioningtherelianceofimitation

23

inhibitiononadistinctlysocialmechanism(Butleretal.,2015;Craccoetal.,2018;

Genschowetal.,2017).Insteadofadistinctlysocialmechanism,imitationcontrolmay

involvedomain-generalcognitivecontrolmechanisms,whicharealsoengagedduring

thecontrolofothernon-socialpre-potentresponsetendencies(Heyes,2011;Cooperet

al.,2012).Indeed,thedual-routemodelofautomaticimitationproposedbyHeyes

(2011)canexplainthecontrolofautomaticimitativetendencieswithoutassuminga

relianceonaself-otherdistinction.Themodelsuggeststhatlikeotherstimulus-

responsecompatibilitytasks,imitationcontrolismediatedbylong-termstimulus-

responseassociationswhichareaproductoflearning.Inlinewiththis,the

computationalmodelputforthbyCooperetal.(2012)furthersubstantiatesthisnotion

bydemonstratingthatspatialandimitativecompatibilityeffectsdependonsimilar

cognitiveprocesses,andanybehaviouraldifferencesareaccountedforbydifferentsets

ofinputnodesforspatialandimitativeeffectsinageneraldual-routeframework(but

seeBerthental&Scheutz(2013)foracritiqueofthismodel).

Eventhoughitispossiblethatimitationandspatialcompatibilityrelyona

partlysharedsetofcognitiveprocesses,thisdoesnotaddressthequestionofwhether

theseprocessesalsorelyonsimilarordistinctneurobiologicalmechanisms.The

currentmeta-analysissuggeststhattheselectionmechanisminimitationinhibitionis

guidedbyadomain-generalmultipledemandsystem,whichisalsoengagedduringthe

inhibitionofothernon-socialexternalinfluences.However,alackofengagementof

mPFC(andpossiblyrTPJ)inimitationcontroldoesnotimplythattheydonotalsoplay

aregulatoryroleinimitationcontrol.Forexample,mPFChasbeendemonstratedto

exertatop-downinfluenceduringmodulationofimitationviadirectgaze(Wangetal.,

2011).Inaddition,rTPJshowedahigherresponsewhenaninteractionpartnerwas

believedtobehumanandlookedhumancomparedtowhentheseanimacycueswere

24

absent(Klapperetal.,2014).ThesefindingssuggestthatmPFCandrTPJmayplaya

regulatoryroleinimitationcontrolandmaybefunctionallyconnectedtoother

networkswithoutbeingdirectlyengaged(Burnett&Blakemore,2009).Thecurrent

findingssuggestthatfutureworkshouldpostulateandtestmorecomplexmodelsof

imitationcontrol,whichextendbeyondtheoperationsofthetheoryofmindnetwork.

Inasimilarmanner,othersocio-perceptualcircuits,whichextendbeyondthe

MDnetwork,mayalsobeinvolvedwheninhibitingautomaticimitativetendencies.In

thisregard,itisimportanttonotethedistinctionbetweeninput-andmechanism-

specificity.Ofcourse,theinputintheimitationinhibitiontaskcanbereadilyidentified

asemanatingfromasocialentityi.e.ahumanhand.Thus,theobservedinputisclearly

socialinthesensethattheobservedagentoffersopportunityforsocialinteraction.

Althoughtheperceptualinputissocial,adomain-generalselectionmechanismmaystill

operateinimitationcontrol.Indeed,itispossiblethatthesameselectionmechanism

operatesacrossbothsocialandnon-socialcontexts.Inthecontextofimitation,

therefore,domain-specificactionobservationandpersonperceptionnetworksmay

functionallyinteractwithdomain-generalcontrolmechanismsintheMDnetwork(see

Figure1).Thus,similartootherdomainsofsocialinformationprocessing,aninterplay

betweendomain-generalanddomain-specificnetworksmayresultinthecontrolof

automaticimitativetendencies(Baldauf&Desimone,2014;Spunt&Adolphs,2017;

Zakietal.,2010).Thus,theengagementofdomainspecificanddomaingeneralneural

networksinimitationcontrolmaybemorecomplicatedthatwhatcurrentmodelsof

imitationsuggest.Consequently,theoriesthatmovebeyondaneatdivisionandposit

linksbetweendomain-generalanddomain-specificsystemsinimitationcontrolneedto

begivengreateremphasisinfuturework(Barrett,2012;Spunt&Adolphs,2017;

Michael&D’Ausilio,2015;Binney&Ramsey,2019).

25

Inconclusion,thecurrentmeta-analysisprovidesevidencethattheselection

mechanismwheninhibitingautomaticimitativetendenciesisguidedbytheregionsof

thedomain-generalmultipledemandnetworkratherthanadomain-specificsystem

relatedtosocialcognition.Ourmeta-analysisquestionstheroleofmPFCandrightTPJ

inimitationcontrol,andsuggeststhatcurrentneurocognitivemodelsofimitation

controlneedfurtherrevisioninordertoaccountforthemorecomplexnatureof

functionalinterplaybetweendomain-generalanddomain-specificsystems.

26

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Table1.Dataextractedfromthestudiesincludedinthemeta-analysis.

Authors Year Sample Contrasts Fixed/RandomEffectsModel

MNIorTalaraichcoordinates

GC SC IC

Brassetal. 2001 10 x Fixed Talaraich

Brassetal. 2005 20 x Fixed Talaraich

Spengleret

al.2009 20 x Random Talaraich

Crescentini

etal.2011 19 x Random MNI

Wangetal. 2011 20 x Random MNI

Mengotti

etal.2012 22 x x Random MNI

Cross&

Iacoboni2013 24 x x Random MNI

Crossetal. 2013 20 x x

Klapperet

al.2014 19 x Random MNI

Marshet

al.2016 24 x x x Random MNI

Dardaet

al.(Exp1)2018 28 x Random MNI

Dardaet

al.(Exp2)2018 50 x x x Random MNI

Campbell

etal.

2018 x Random MNI

TOTAL=

11 300

NB:GC=GeneralCompatibility,SC=SpatialCompatibility,IC=ImitativeCompatibility

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Table2.Contrastsusedinthemeta-analysisforgeneral,spatial,andimitative

compatibility.

Authors Year GeneralCompatibility SpatialCompatibility ImitativeCompatibility

Brassetal. 2001 GeneralIncompatible>

GeneralCompatible

Brassetal. 2005 GeneralIncompatible>

GeneralCompatible

Spengleretal. 2009 GeneralIncompatible>

GeneralCompatible

Crescentiniet

al.2011 GeneralIncompatible>

GeneralCompatible

Wangetal. 2011 GeneralIncompatible>

GeneralCompatible*

Mengottiet

al.2012 Non-specular>

Specular^

SpatiallyIncompatible>

SpatiallyCompatible

Cross&

Iacoboni2013 GeneralIncompatible>

GeneralCompatible

SpatiallyIncompatible>

SpatiallyCompatible

Crossetal. 2013 GeneralIncompatible>

GeneralCompatible

GeneralCompatibility>

SpatialCompatibility

Klapperetal. 2014 GeneralIncompatible>

GeneralCompatible*

Marshetal. 2016 GeneralIncompatible>

GeneralCompatible

SpatialIncompatible>

SpatiallyCompatible

ImitativelyIncompatible

>ImitativelyCompatible

Dardaetal.

(Exp1)2018 GeneralIncompatible>

GeneralCompatible

Dardaetal.

(Exp2)2018 GeneralIncompatible>

GeneralCompatible

SpatialIncompatible>

SpatialCompatible

ImitativeIncompatible>

ImitativelyCompatible

Campbellet

al.

2018 GeneralIncompatible>

GeneralCompatible

No.ofstudies 12 4 3

No.ofcontrasts 13 4 3

No.offoci 142 42 20

Table2showsthecontrastsusedinthecurrentmeta-analysis,andthenumberof

contrasts,foci,andstudiesforeachcompatibilitytype(general,spatial,andimitative).

*Collapsedacrossconditions;forWangetal.,2011:collapsedacrossdirectandaverted

gaze,forKlapperetal.,2014:collapsedacrossbelief(motion-capture,computer

animation)andform(human,non-human).

^Non-specular>Speculari.e.{(spatiallyincompatibleandimitativelycompatible)+

(imitativelyincompatibleandspatiallycompatible)>generalcompatible)}]

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Table3.Areasconsistentlyactivatedforgeneralcompatibility,spatialcompatibility,and

imitativecompatibility.

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GENERALCOMPATIBILITYRegion MNI MaximumP No.ofVoxels Threshold

x y zRightTPJ 60 -46 22 0.42 1 ^**

RightTPJ 56 -46 32 0.41 1 ^**

Rightsupramarginalgyrus

56 -36 36 0.44 9 ^**

RightIPL 60 -34 34 0.43 2 ^**

RightIPL 52 -30 38 0.37 5 ^**

RightMFG 34 0 54 0.45 15 ^*

RightSFG 26 -2 64 0.37 46 ^*

LeftInsulaLobe -36 14 0 0.32 453 **

-34 12 -2 213

-36 18 2 240

RightInsulaLobe 38 16 4 0.36 405 **

34 18 0 172

46 12 2 75

38 16 6 158

RightIFG 46 14 10 0.28 1269 *

44 16 -4 74

28 24 -4 44

32 12 0 41

46 22 2 113

56 10 2 116

28 20 6 105

36 26 6 66

56 16 6 128

52 12 14 219

48 2 22 92

40 8 22 132

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Table3showsareasconsistentlyactivatedforgeneralcompatibility,spatial

compatibility,andimitativecompatibility.MaximumPstandsforthemaximum

proportionofstudiesexhibitingtheeffectatthepeakdensityweightedbysamplesize.

MNI=MontrealNeurologicalInstitute(MNI)standardstereotaxicspacecoordinates.

Thevoxelsizeis2×2×2mm

3

.

*Clusterswithstandingp<.01clusterextent-basedthreshold.

**Clusterswithstandingp<.001clusterextent-basedthreshold.

^Clusterswithstandingtheheight-basedthreshold.

50 8 28 139

SPATIALCOMPATIBILITY

LeftIPL -36 -40 48 0.78 8 ^

Rightsuperiorfrontalgyrus

24 -4 58 0.78 190 ^

24 -6 54 56 ^

24 -4 60 134 ^

IMITATIVECOMPATIBILITY

Leftsupramarginalgyrus/IPL

-48 -28 34 0.73 11 ^

Rightsupramarginalgyrus/IPL

48 -26 44 0.73 18 *^

52 -30 42 7

46 -26 46 11

38

Figure1.Brainnetworksassociatedwiththecontrolofautomaticimitation.

Figure1.Brainnetworksassociatedwiththecontrolofautomaticimitation.

Thisgraphicalrepresentationdividesimitationcontrolintotwoconstituentprocesses–

representationofthepersonandtheiraction,andtheselection(control)oftheright

actiontobeexecuted.Inthecontextofautomaticimitation,therepresentationsystem

consistsinface,body,biologicalmotion,andactionperception.Theneuralsubstrates

forpersonandactionperceptionspanthefusiformgyrus,occipitotemporalcortex,and

posteriorsuperiortemporalsulcus,aswellasthemirrorneuronsystem(Kanwisher,

2010;Caspers,etal.,2010).Thecontrolorselectionsystemconsistsinabrainnetwork

thatiseitherdomain-general(i.e.themultipledemandnetwork)ordomain-specific(i.e.

thetheory-of-mindnetwork).N.B.Abbreviations:MNS=mirrorneuronsystem;IPL=

inferiorparietallobule,IFG=inferiorfrontalgyrus;pSTS=posteriorsuperiortemporal

sulcus;OT=occipito-temporalcortex;FG=fusiformgyrus,MD=multipledemand

network;ToM=theory-of-mindnetwork;mPFC=medialprefrontalcortex;PMC=

primarymotorcortex;dlPFC=dorsolateralprefrontalcortex;TPJ=temporo-parietal

junction.Thebidirectionalarrow“”indicateslinksbetweenthedifferentnodesof

imitationcontrol.

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Figure2.ConsistencyofbrainactivationfromtheMKDAAnalyses.

Figure2.ConsistencyofbrainactivationfromtheMKDAAnalyses.

Brainareasthatareconsistentlyengagedforgeneralcompatibility(A),spatial

compatibility(B),andimitativecompatibility(C).Voxelsthatexceedtheheight-based

threshold(p<.05,FDRcorrected)inouranalysisappearinyellow,andthosethatexceed

theclusterextent-basedthresholdappearinorange(p<.001)andred(p<.01).

Figure3.OverlayoftheMKDAmapswiththeToMandMDnetworkmasks.

Figure3.OverlayoftheMKDAmapswiththeToMandMDnetworkmasks.OverlayofthedensitymapswiththeToMandMDnetworkmasksallowedforidentificationofoverlapbetweenregionsthatwereconsistentlyactivatedintheMKDAandtheToMandMDnetworks.Forallcompatibilitytypes(general,imitativeandspatial),allregionsthatpassedheightorextent-basedthresholdingoverlappedwithregionsintheMDnetwork(A).Additionally,onecluster,whichshowedconsistentactivationforgeneralcompatibility,alsooverlappedwiththerightTPJintheToMnetwork(B).TherewasnooverlapwiththemPFCnodeoftheToMnetworkforanycompatibilitytype.

Figure4.OverlayofContrastIndicatorMapswithrTPJ.1

2

Figure4.OverlayofContrastIndicatorMapswithrTPJ.3

TheToMnetworkmaskforrTPJoverlaidwiththecontrastindicatormapsofallstudies4

usedforgeneral(N=12;A)imitative(N=3;B)andspatial(N=4;C)compatibility.There5

wasoverlapbetweencontrastindicatormapsforgeneralcompatibilityandspatial6

compatibilitywithrightTPJ.Thereisnooverlapbetweencontrastindicatormapsfor7

imitativecompatibilityandthesamerightTPJmask.8

Abbreviations:IC=ImitativeCompatibility;SC=SpatialCompatibility,GC=General9

Compatibility10

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Ethicsstatement37

Thecurrentworkwasameta-analysisofexistingdataandtherewerenoethical38

considerations.39