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The contribution of the lesion approach to the
neuroscience of creative cognition
Marcela Ovando-Tellez, Theophile Bieth, Matthieu Bernard, Emmanuelle
Volle
To cite this version:
Marcela Ovando-Tellez, Theophile Bieth, Matthieu Bernard, Emmanuelle Volle. The contribution of
the lesion approach to the neuroscience of creative cognition. Current Opinion in Behavioral Sciences,
Elsevier, 2019, 27, pp.100-108. �10.1016/j.cobeha.2018.10.011�. �hal-02271207�
The
contribution
of
the
lesion
approach
to
the
neuroscience
of
creative
cognition
Marcela
P
Ovando-Tellez
1,
Theophile
Bieth
1,
Matthieu
Bernard
and
Emmanuelle
Volle
Psychologicalandrecentneuroimagingfindingsindicatethat creativityreliesonabalancebetweenassociativethinkinglikely supportedbythedefaultmodenetworkandcognitivecontrol processessustainedbycontrol-relatednetworksincluding frontoparietalregions.Exploringpatientswithbrainlesions allowstestingthismodelandascertainingamorecausallink betweencreativeprocessesandbrainsystems.Resultsfrom thelesionapproachprovideargumentsforthecriticalroleof thedefaultmodenetworkandthefrontoparietalcontrol networkforassociativeandcontrolledprocesses,respectively, andidentifycriticalnodeswithinthesenetworks.Thefewlesion studiesthathavebeenperformedalsosuggestafunctional specializationofseveralprefrontalregionsfordistinctcreative processes.Inthecurrentreview,weintegratetheresultsof lesionstudieswiththefindingsemergingfrombothrecent functionalimagingandnon-invasivebrainstimulationstudies, inanattempttobetterunderstandthecognitiveandbrain mechanismsofcreativityorthepotentialwaystoimprovethis knowledge.
Address
FRONTLAB,Institutducerveauetlamoelle(ICM)–SorbonneUniversite´, INSERM,CNRSHoˆpitalPitie´ Salpeˆtrie`re,47,bddel’hoˆpital,F-75013, Paris,France
Correspondingauthor:Volle,Emmanuelle(emmavolle@gmail.com)
1
Theseauthorsequallycontributedtothereview.
Introduction
Acreativeproductioncanbeviewedbothastheresultof high-level control functions or top-down processes (includinginhibitorycontrol)andastheresultofa relax-ationofone’sconstraintsorinhibitions,possiblyfavoring spontaneous associative thinking and bottom-up pro-cesses. These two views make opposite predictions regarding the role of the prefrontal cortex (PFC), that support controlled functions, in creativity. Recent
cognitive modelstry to conciliate theseviews and con-siderspontaneousassociativeandcontrolledprocessesas complementary rather than paradoxical in the creative process[1–5].Withthedevelopmentofnetwork neuro-sciencebasedonfunctionalconnectivity,the neuroimag-ingofcreativecognitioninhealthysubjectshavestarted toclarifythemultiplebrainsystemsinvolvedin associa-tiveandcontrolledcreativeprocesses,andtospecifythe placeofthePFCinthesesystems. Thelesionapproach may be especially useful in complementing functional imaging toward a better understanding of the cerebral substrateofcreativity,byidentifyingcriticalnodesinthe diversityofbrain networksreportedin functional imag-ing, and precising their specific role in the creativity processes[6].Surprisingly,very fewlesion studieshave investigatedcreativeabilitiesinbrain damagedpatients [7–14,15,16,17,18](Table1).Focusingonthe neurosci-entific literature of creativity, especially coming from patients, this review will explore not only whether the PFCiscriticalforcreativeabilities,butmoreimportantly whatprefrontal systems are necessaryfor associative or controlledcreativeprocesses.
Recent
cognitive
and
neuroimaging
findings
Thecognitiveneuroscienceof creativityprovides abun-dantexperimentalevidenceoftheimportantroleof PFC-dependentcognitive control functions in creative abili-ties. These functions include inhibition of prepotent responses[19–21],controlledretrieval[22–24]and work-ing memory [25,26]. Neuroimaging data using task-relatedactivationandfunctionalconnectivityin healthy subjects are consistent with this view. Several meta-analysesofcreativity-relatedactivationstudieshave reli-ablyshown thatlateralfrontalandparietalareasarethe mostrecruitedset ofregionsin creativitytasks [27–29]. Functional connectivity analyses have highlighted the importance of the control-related networks including the frontoparietal network in creativity [30,31]. The lateralPFCregionmaybeespecially recruitedfor inhi-bition of dominant responses [20], controlled retrieval [23,24],andselectionorevaluationprocesses[32].
Aside from the deliberate control processes, creative thinkingalsoinvolvesmorespontaneousassociative pro-cesses.Theroleof associativethinkingabilitiesin crea-tivity may rely on the organization of associations between elements of one’s semantic knowledge that determinesthe abilityto generateand combineremote
Table 1
Patient group studies on creative cognition in adults. The table includes studies in patients that related creative abilities to an anatomical location of a lesion or neurodegenerative impairment. Case reports already described in a previous review [60] are not included
Study Task Region Network Effect
Group studies of focal lesions
Reverberi et al. [7]a Match stick problem-solving Lateral PFC versus controls N.A. " correct responses (type C)
‘Pure’ medial PFC versus controls and versus lateral PFC N.A. # correct responses (type A) Shamay-Tsoory et al. [10]b TTCT and AUT mPFC versus controls and versus parietotemporal patients N.A. # total score & originality
mPFC+IFG versus controls and versus parietotemporal patients
N.A. # total score & originality
Right mPFC region N.A. # originality with " lesion size
Left parietotemporal patients N.A. " originality with " lesion size Identified a subgroup of patients with mainly left
parietotemporal or IFG lesions with higher originality index
N.A. " originality
Abraham et al. [11]c AUT Lateral PFC versus controls N.A. # originality, fluency
Imagery task Lateral PFC versus controls N.A. # practicality
Imagery task Temporoparietal patients versus controls N.A. # practicality
CET Temporoparietal patients versus controls N.A. More constrained
Concept expansion Tested but no significant lesion location N.A.
RAT Tested but no significant lesion location N.A.
Duff et al. [12] TTCT Hippocampal damage versus controls N.A. # originality, fluency, flexibility & elaboration Ghacibeh et al. [13] TTCT Left versus right anterior temporal lobectomy N.A. No difference between left & right
lobectomy (no control group)
Warren et al. [15] RAT Hippocampal damage versus controls N.A. # correct responses
VSLM and disconnection-deficit mapping on focal lesions
Bendetowicz et al. [17] RAT-like Left rostrolateral PFC, FMT, ATR, FSP Left FPCN # remote associates combination Word-association task Right rostromedial PFC, Cingulate tract DMN # remote word associations Group studies on neurodegenerative diseases
Rankin et al. [8]d Figural TTCT FTD versus controls N.A. # resistance to premature closure
SD versus controls N.A. # fluency, originality, elaboration & resistance to premature closure
De Souza et al. [9] TTCT FTD versus controls N.A. # originality, fluency, flexibility
FTD versus Parkinson patients N.A. # originality, fluency, flexibility VBM-like analysis on SPECT data identified the rostral PFC,
posterior parietal and laterotemporal regions
N.A. Integrity of these regions correlated with TTCT scores
Canesi et al. [16] ATTA PSP versus controls, versus Parkinson patients and versus MSA patients
N.A. # originality, fluency, flexibility, elaboration
ATR: anterior thalamic radiations; ATTA: abbreviated Torrance test for adults; AUT: alternative uses test; CET: constraints of examples task; DMN: default mode network; FMT: frontomarginal tract; FPCN: frontoparietal control network; FTD: frontotemporal dementia, that is, frontal variant of frontotemporal lobar degeneration characterized by predominantly frontal atrophy; FSP: frontostriatal projections; IFG: inferior frontal gyrus; mPFC: medial prefrontal cortex; PFC: prefrontal cortex; MSA: multiple system atrophy characterized by subcortical and cortical damage in several lobes; PSP: Progressive supranuclear palsy characterized by atrophy in frontal cortex, basal ganglia, and midbrain; RAT: remote associates task; SD: semantic dementia, that is, temporal variant of frontotemporal lobar degeneration characterized by predominantly temporal atrophy; TTCT: Torrance test of creativity thinking; VBM: voxel-based morphometry; VSLM: voxel-based lesion-symptom mapping analysis.
a‘Pure’ medial PFC refers to the subset of the medial group that had pure medial or orbitofrontal damage. Performance of the whole group of patients in the different problem types with
predominantly medial PFC lesions did not differ significantly from lateral PFC and control groups.
b
In this study, the comparison between the IFG group and controls or parietal patients was not significant. The IFG group had higher performance than the mPFC group in the AUT task.
c
Only significant results reported at a p value<0.05 are included in the table. This study also tested patients with basal ganglia lesions, but their performance was not significantly different from controls at p< 0.05.
associations[33].Insupportofthistheory,psychological studieshaveshownthatmorecreativepeoplehavemore flexiblesemanticassociations,allowing themtoconnect more distant concepts or words [34–36,37,38,39,40]. Althoughthecerebralsubstratesofassociativeprocessing arenotelucidated, recentevidencesupportstherole of thedefaultmodenetwork(DMN)inunconstrained asso-ciativethinking [40] and more broadly in spontaneous cognition [41] including mind wandering [42,43] and contextualassociations[44].Severalstudieshaveshown that the morphometry and functional connectivity of DMN regionscorrelate with creative performance [45– 51].Consistentwith therole ofsemanticassociationsin creativity,semanticmemoryregionsarealsoimportantfor creative abilities[11,27,28]and have both overlaps and functionalinteractionswiththeDMNthatremaintobe clarified[20,52,53].
Overall, the cognitive neuroscience of creativity now considersthatcreativeabilitiesresultfromaninteraction orabalancebetweenassociativeandcontrolledprocesses [1–5]. Recent functional connectivity studies strongly support this viewby demonstrating that two main net-worksinteractduringcreativitytasks:alateral frontopar-ietalcontrolnetwork(FPCN),knowntosupportcontrol functions,andtheDMN,thathasbeen relatedto asso-ciative thinking and spontaneous cognition [31,32,54,55].The interactionbetweenthesesystems might be mediatedby theSalience network [30] or by regionsofthesenetworksactingasconnectorhubs.The identificationof largescalenetworksthatinvolve differ-entpartsofthePFCisanimportantstepinunderstanding thecerebralbasisforcreativityandoffersnewpredictions regardingwhichcreativitymechanismscanbeimpacted byspecificlesionlocations.
Critical
role
of
the
DMN
and
FPCN
for
creativity
(
Table
1
)
ToexplorewhethertheDMNandFPCNarecriticalfor creative processes, Bendetowicz et al. [17] performed a lesionstudyonpatientswithsinglefocalfrontallesions. To assess creative abilities,the authors used the Com-bined Association Task, an adaptation of Mednick’s RemoteAssociatesTask(RAT),inwhichthreeunrelated cuewordsarepresented,andthesubjecthastoprovidea solution word related to all three cue words. Because Mednick’stheorypredictsthatassociativeprocessesare requiredduring RAT-like tasks, thesame patients per-formed a simple word-to-word association task. In this task, patients were instructed to provide the first word thatcametomindinresponsetoagivencuewordandan unusual associate of the same cue word. The results showed that damage to the left FPCN impaired the performance on the RAT-like task, while damage to theDMNimpairedtheabilitytogenerateunusualword associations. Hence, these results confirm recent
functional connectivity findings [30,31] by showing thecrucialroleof bothDMNandFPCN increativity.
Thecriticalrole of theDMNin creativity isconsistent withpreviouslesionstudiesthatshowedadeficitinboth RAT[15]anddivergentthinking[12]tasks inpatients withdamagetothehippocampus,aDMN-relatedregion. A rostromedial PFC damage, another region that is thoughttobelongtotheDMN,hasbeenassociatedwith adivergentthinkingimpairmentinShamay-Tsooryetal.’ sstudy[10],whichhighlighteddifficultiesin generating originalideasinthesepatients.However,thisresultwas not replicated by Abraham et al., who did not observe significantdeficitsin divergentthinking in polarand/or orbitofrontal patients [11]. A medial PFC lesion also appearstoimpactmindwandering[56],amentalactivity shown to be related to creativity abilities. In line with lesion studies, direct brain stimulation studies using transcranial direct-current stimulation (tDCS) have shown that stimulating themedial PFC could improve theremotenessof wordassociations duringa word-gen-erationtaskincertain conditions[57,58],and inhibiting this region could also decrease mind wandering [59]. According to Bendetowicz et al. [17], the DMN, and especially itsmedial PFC regions, maybe criticalfor a particular thinking type or mode characterized by a spontaneous and associative spread of thoughts that is essential in RAT-like tasks. Voxel-based lesion deficit mappinganalyses revealed that when a lesion affected the rostromedial prefrontal region, patients produced morecommonortypicalwordassociates,withorwithout the instruction to think unusually, which is consistent witha‘rigidity’insemanticassociations,andmayexplain thatthesepatientsalsohadpoorcreativityperformance. The ‘rigidity’ of semantic associations that may results from aDMN lesion impacts the generation of unusual associations,whichimpairsremotethinkinginboth con-vergentanddivergenttasks.Thisinterpretationsupports Mednick’shypothesis,onlytestedpreviouslyin healthy subjects.The organization of semanticassociations also likelyrelatesto semanticmemory thathas beenshown criticalfordivergentthinking[8;butseeRef.13]. How-ever,therelationshipsbetweentheDMNandsemantic memory networkfor associative thinking remainsto be clarified.
ThecriticalroleoftheFPCNhasbeenshowninseveral patientstudies.Inpatientswithafrontal neurodegenera-tive disease, De Souza et al. [9]showed that divergent thinking scores correlated with atrophy in prefrontal, temporal, and parietal regions that overlap with the FPCN.Rankin etal. [8,see alsoRef. 16]reported that both frontal and temporal neurodegenerative diseases affecteddivergentthinking.Inpatientswithfocallesions, aleftrostrolateral PFClesion hasbeenassociated with decreased performance on RAT-like tasks [17]. More caudal lateral PFC lesions as explored by Abraham
et al. [11] were associated with decreased fluency and originalityof ideasproducedindivergentthinkingtasks andtemporoparietallesionswithanincreasedfixationon examples.Bothlateralfrontalandtemporoparietallesions impacteddivergentthinkingtasksandacreativeimagery task[11].Thesedatasuggest thatseveralregionsofthe FPCN are essential to various creativity tasks. On the contrary,otherfindingssuggestedanincreasedoriginality of ideasafteraleftposteriorparietotemporallesion,and possiblyaleftinferiorfrontallesion[10,seealsoRef.14], and better problem solving abilities aftera lateral PFC lesion [7]. A few patient reports have described the emergence or improvement of creative artistic abilities after a frontotemporal disease ([60,61] for reviews). Hence, patientstudiesprovide inconsistent conclusions regarding the critical role of frontoparietal regions in creativity.Similarly,non-invasivebrainstimulation stud-iestargetingtheleftlateralprefrontalcortexhaveshown divergenteffectsoncreativeperformance:bothcathodal [62,63,64] andanodal[65–68]tDCS of theleftlateral PFC,aimingtosuppressorelicittheactivityofthisregion respectively, have been reported to increase creative abilities. Overall, the few lesion and brain stimulation studiesthathavebeenconductedconfirmtheimportance of FPCN regionsfor creativity,but some ofthem chal-lenge theroleof theleftlateral PFC.Thisdiscrepancy maybeexplainedbythecombinationof:firstly,alackof precisionregardingtheexactlocationof lesions/stimula-tion and the networks impacted by them, secondly, a functional heterogeneity of prefrontal regionsregarding creativity processes and thirdly, differences in the pro-cesses most required by the creativity tasks that have been used.
Specialization
of
the
lateral
PFC
for
distinct
creative
mechanisms
(
Figure
2
)
The PFC appearsto be themostconsistentlyexplored and/or reported regionin lesion (and brain stimulation) studies,whichmayallowtoexaminewhetherafunctional PFC organization for creativity canemerge. It is likely thatpatientandbrainstimulationstudieslackanatomical precision and targetdistinctareasof thePFCwithinor outside the FPCN. Except for Bendetowicz et al. [17], lesion studies on creativity did not use voxel-based methods to specify the locationof thecritical area and did not analyze which networks were affected by the lesion. By using these approaches [69], Bendetowicz et al. [17] were ableto identify aspecific area that was critical for verbal creativity,and clarifiedto which net-worksitwasconnected.IntheleftFPCN,the rostrolat-eral PFC region and its connections were critical for solvingRAT-likeproblems(Figure1).Yet,patientswith a lesion in this region did not have any difficulties generating close or remote word associates, indicating that the left rostrolateral PFC plays a critical role in RAT-liketasks byaffecting controlrather than associa-tiveprocesses.ThepivotalroleoftherostrolateralPFCin
RAT-liketasksparallelsmorphometryfindingsinhealthy subjects,showingthatthevolumeoftheleftrostrolateral PFCwasassociatedwithbetterperformanceinsuchtask [70]. In addition, a meta-analysis of functional MRI studies showedthat tasks involving thecombination of remoteelementsactivatedtheleftrostrolateralPFCmore than other creativity tasks [27]. Combined with the established of the left rostrolateral PFC in relational integrationandmultitasking,andconsistentwiththelink between theRAT and relational reasoning[71–74,75], these data suggest that the role of this region is to integratetherelationshipsbetweenseveralpairsofwords duringRATtrials,possiblybycoordinatingorbranching theassociative andcontrolledprocessing.
In posteriorareas, afunctional specializationof distinct prefrontal subregionsorFPCN subregionsforcreativity processeshasbeenproposed[24](Figure2).Forinstance, ventralanddorsalprefrontalregionsareproposedtoplay a role in the generative versus evaluative steps of the creativeprocess,respectively.Althoughfunctional imag-ing studies have highlighted the key role of the left inferior frontal gyrus in creativity [20,23,27,40,76,77], several studies suggested that idea generation may improvewhensuppressingitsactivity.Brainstimulation studiesthattargetedtheleftinferiorfrontalgyrusshowed thatinhibitingthisregionimprovedideagenerationina divergentthinkingtask[62,64,78,79],especiallyifitwas
Figure1
Lesion method
fMRI method VBM method
ConvergingresultsontheroleoftheleftrostrolateralPFCincreativity. Onabrainsurfacerenderingisdisplayedtheoverlapofthecritical lesionlocationforRAT-likeperformanceinpatients(red;[17]),a morphometrymapofbrainregionswhichstructurecorrelatedwith RAT-likeperformanceinhealthysubjects(green;[70])andresultsfrom ameta-analysisoffunctionalimagingstudyshowingtheregionsthat weremorerecruitedincombinationtasksrelativetofreegeneration tasks(yellow;[27]).
combined with a right inferior frontal stimulation, and suggested that the activity of the ventrolateral PFC is deleterioustotheideageneration step.One hypothesis thathasbeenput forwardisthatsomeofthecontrolled processessupported bythe PFCN are impaired aftera left ventrolateral PFC damage, releasing spontaneous associativeprocessingandspontaneousflexibility. Relax-ingthe control onassociative thinkingmay benefitthe generationoforiginalideasinsometasksandconditions [67,68].However,thisexplanationquestionsthenatureof the interaction between left inferior frontal gyrus and DMN which functional connectivity has been demon-stratedtoincreaseduringideagenerationandtocorrelate with creative abilities [31,76,77]. Alternatively, decreasing left lateral prefrontal activity may unfilter and increase the availability of bottom-up perceptual information processed in posterior occipitotemporal regions, which might be explained by theparticipation oflateralPFCsubregionsinothernetworksincludingthe attentional networks [2,54,62]. Another hypothesis that hasbeenproposedtoexplaintheimprovementofcertain
problemsolvingabilitiesafterdamage[7]orbrain inhibi-torystimulation[63]of theleftlateral PFCisthatthis regionplays a rolein sculpting the responsespacein a givensituation,resultinginconstrainingthefieldofideas directlyavailable.AlteringthefunctionofthelateralPFC mayreleasethis constrainingroleof thecontext.
Althoughaconstrainingroleoftheleftinferiorfrontalgyrus maybeconsistentwithitscriticalroleincontextualcontrol [80],itsnegativeinfluenceonideagenerationmayseemto contradictaseriesof studiesthathavedemonstratedthe roleof thisregion in the controlled retrievalof memory [23,53,81–83]. Specifically, patients withleft inferior frontal lesionwereshowntobeimpairedinretrievingdistantword associates,suggestinganimpairmentingeneratingunusual associationsorideas[84].Thepotentiallimitingroleofthe lateralPFCinideagenerationandoriginalityalsoremains difficulttoreconcilewithpatientstudiesthatshowedthe crucialroleoftheinferiorPFCininhibitionofdominant responses[85–87].Todate,twomainhypothesesof pre-frontalorganisationhavebeen proposedto reconcilethe
Figure2
Creativity
Associative
thinking
DMN and MemN
Controlled
processes
FPCN and SalN
Spontaneous semantic associations- Search constraint / contextual control - Inhibition of spontaneous flexibility
- Inhibition of prepotent ideas (right?) - Controlled retrieval and selection (left?)
- Filtering of bottom up information* Combination of remote elements / relational integration
Tentativesummaryofthefindingsoflesionstudies.Theschemarepresentsthereportedeffectofbrainlesions,whichdecreased(plainarrows)or increased(emptyarrow)creativeperformance,andproposeshypotheticalprocessesthat,whenaffected,canexplaintheseeffects.Pleasenote thatthisschemaisnecessarilysimplisticanddoesnotdepictallpossiblemechanismsandnetworkdamagesbywhichbrainlesionscould theoreticallyimpactcreativity.*theexactlocationoflateralprefrontallesions(ventraland/ordorsal)andnetworkdisruption(FPCN,salienceor attentionalnetworks)thatmayfavorcreativeperformanceareunclear.DMN:defaultmodenetwork;FPCN:frontoparietalcontrolnetwork;MemN: semanticandepisodicmemorynetworks;SalN:saliencenetwork.
beneficial and deleterious effects of caudal prefrontal lesions/brainstimulationoncreativity.Thefirstone con-siders that ventral and dorsal caudalPFC regions have opposite rolesin the generativeand evaluative stepsof divergentthinking.TheactivityoftheventrolateralPFC maybedeleterioustothegenerationstepthatrequiresless controlprocesses[32,64],whileotherprefrontalregions areimportant forthemorecontrolledevaluationstep[67]or fortheinhibitionofconstraints[20].Thesecondoneisto considerabalancebetweenleft andrightventrolateralPFC rather than the role of each region separately [78]. For instance, the left and rightventrolateralPFC mayhave specificroles,inconstrainingthesearchaccordingtothe contextandinhibitingtheinappropriateorlessinteresting responses,respectively.Overall,the specializationofthe caudalPFCforcreativityprocessesaccordingtoan inferior-superiororaleft-rightaxisremainstobetested(Figure2).
Finally,apotentialfactorinfluencingthereportedresultsis thatdifferentcreativitytasksrequire adifferentbalance betweenassociativeandcontrolledprocesses,sothat alter-ingcontrolledprocessesmayormaynotimpactagiventask [67].ExistingtDCSstudiesmaysupportthisexplanation. Infact,toourknowledge,alltDCSstudiestargetingtheleft lateral PFC with anodal stimulation showed improved performance in RAT tasks [65,88,89].All tDCS studies targetingthesame regionwithcathodalstimulationshowed an improvement of divergent thinking tasks [62,64,78,79].Onlyonestudyshowedanimprovement of divergentthinkingafteranodalstimulationoftheleft dorsolateral PFC, but it was conditioned by a priming instruction to think divergently [66], which may have involvedmorecontrolledprocessesthandivergent think-ingtasksusuallyrequire.Thesedatasuggestthat original-ityindivergentthinkingtasksmaydependmoreon spon-taneousassociationscomputedbytheDMNwhile RAT-liketasks additionallyrequirethelateralPFC, likelyfor controlledprocesses.Problemsolvingtasksvaryaccording tocontroldemands[63].Therelianceoncontrolled pro-cessestosolvethedifferentcreativitytaskmayshapethe performanceobservedafteraprefrontallesion.
Hence,thespecificroleofdistinctprefrontalsubregionsin creativityprocessesremains tobeclarifiedandintegrated withfindingsfromotherfieldsofcognitiveneurosciences. Although thelesionapproachmaybe especiallyusefulto address this question, the conclusions that canbe drawnfrom existing patient studies are limited by the fact that they rarely consideredthefunctionalandconnectivepropertiesofthe damagedareasandexploredarelatively smallnumber of patients.Preciselydefiningthelesionlocationanatomically isthusessentialinfuturestudiesascloseregionsinfrontal, temporalandparietallobesarefunctionallyheretogeneous andmaybelongtodistinctnetworks,includingtheFPCN, DMNbutalsosalienceandattentionalnetworks[90].The useofvoxel-basedlesionmethodswithlargersamplesize couldimprovetheanatomicalresolutionofbrain–behavior
correlations,andismorecomparabletofunctionalimaging findings.Inaddition,connectivityapproachesinpatientsare neededtoidentifythenetworksthatareanatomicallyand functionally impacted by the lesion [69] (or the brain intervention[91]).Newanatomicalandfunctional connec-tivity methods integrating network-based and lesion approaches in patients are promising avenues for future research on creativity[92]. Such approachesmayhelp to clarifyhowdistinctnetworksandtheirinteractionssupport distinctcreativitymechanisms,toidentifythecriticalhubs allowingtheseinteractions,and,forinstance,todisentangle therole ofdefaultmode,semantic,attention,andcontrol networksincreativity.
Conclusions
Patientstudiescanprovideimportantinformationtothe neuroscienceofcreativitybyidentifyingthecritical net-works and pivotal nodes withinthe networks.The few lesion studiesthathavebeenperformedconfirmed that the integrity of both the DMN and the left FPCN is important for creative performance. In agreement with predictions fromfunctionalimaginginhealthysubjects, theDMNappearscriticalforassociative processingand theFPCNforcontrolledprocesses. Brainlesions affect-ingsomeregionsoftheleftcontrol-relatednetworkmay imbalance the associative and controlled processes involved in creative thinking,affecting creative perfor-mance differently depending on which process is the mostrequiredbythetask.Thelesionapproachalsohelps to clarify the functional organization of the PFC for distinct creativeprocesses,showingamedial-lateral dis-sociationinrostralPFCfor associativeversuscontrolled processes, andsuggesting arostrocaudal lateral speciali-zation fordistinctcontrolled processes.
Thecontributionoflesionstudiestotheneuroscienceof creativitycouldbeenhancedinthefuturebycombining different measures of creativity with anatomical and functionalconnectivitymethodstoidentifythenetworks impactedbythelesion.
Conflict
of
interest
statement
Nothingdeclared.
Acknowledgements
EmmanuelleVolleissupportedbyFRMgrantDEQ20150331725and program‘Investissementsd’avenir’ANR-10-IAIHU-06.MarcelaOvando TellezissupportedbyaCONICYTfunding.TheophileBiethwas supportedbyafundingfrom‘Journe´esdeneurologiedelanguefranc¸aise’.
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