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•  Participantscompletedaforwarddigitspantask(Gathercole&Adams,1993).

•  Participant’sDigitSpanScorewasmeasuredastheproportionofsequencescorrectlyrecalled.

•  AbivariatecorrelationshowedthatDigitSpanScorewassigniGicantlyandpositivelycorrelatedwithage.

• ThefollowingROIswerecreatedbyaveragingcorticalthicknessvaluesforareasofinterest:

• ACC:left/rightrostralanteriorcingulatecortexandcaudalanteriorcingulatecortex

• SPC:left/rightsuperiorparietalcortex• SFC:left/rightsuperiorfrontalcortex• MFC:left/rightrostralmiddlefrontalcortexandcaudalmiddlefrontalcortex

• Associationsbetweencorticalthicknessanddigitspanperformancewereexaminednext.•  SeparatelinearregressionswererunenteringeachROIasthepredictorandDigitSpanScoreasthedependentvariable.

•  Covariates:Totalgraymattervolumeandgender.•  CorticalthicknessineachROIwasasigniGicantpredictorofDigitSpanScore,suchthatthosewithathinnercortexinthespeciGiedareasperformedbetterthanthosewithathickercortex.

• Associationsbetweenageandcorticalthicknesswereexplored.•  SeparatelinearregressionswererunenteringageasthepredictorandeachROIasthedependentvariable.

•  Covariates:Totalgraymattervolumeandgender.•  AgewasasigniGicantpredictorofACCvolume,SPCvolume,SFCvolume,butnotMFCvolume.

Methods

Introduction

Relationsbetweenworkingmemoryandcorticalthicknessinfrontalandparietalregionsinearlychildhood

MorganBotdorf&TracyRigginsUniversityofMaryland,CollegePark

Participants•  181childrenaged4-8years(M=6.27,SD=1.49years,92females)completedthestudy.

•  Participantswerepartofalargerstudyexaminingthedevelopmentofepisodicmemoryinearlychildhood.

MRIData•  T1-weightedhighresolution(1mm3)anatomicalimageswereacquiredfromaSiemens3Tscannerwitha32-channelcoilattheMarylandNeuroimagingCenterusingastandardstructuralMRIscansequence.

•  Freesurferv5.1(Fischl,2012)wasusedtocalculatecorticalthicknessvolumesandtotalgraymattervolume.TheDesikan-Killianyatlaswasusedforcorticalparcellation(Desikanetal.,2006).

•  BoundarylinesbetweenCSF,graymatter,andwhitematterwerevisuallyinspectedtoensureaccuracy.Manualeditsweremadewhennecessary.

Methods:MRIData

Discussion

References

•  Theseresultssuggestthateveninearlychildhood,thereareassociationsbetweenWMabilitiesandthicknessincorticalareasknowntosupportWMinadults.

•  AgewasnegativelyassociatedwiththethicknessofACC,SPC,SFC,butnotMFC.

•  ThicknessineachROIwasnegativelyassociatedwithWMasmeasuredbyDigitSpan.

•  ConsistentwithKharitonova’sGindings(2013),ourresultssupportarelationbetweenSPCandWM,butdidnotsupportamediation.However,ourresultsdidsuggestthatACCisnotonlyassociatedwithWM,butmediatestherelationbetweenageandWM.

•  FutureresearchshouldfocusoninvestigatinglongitudinalchangesinthesecorticalareasastheyrelatetoWMtoincreasethepresentunderstandingoftherelationbetweencorticalthicknessandimprovementsinWMduringchildhood.

• Workingmemory(WM)changesrapidlyinearlychildhood,butitremainsunclearhowcorticalregionsthatsupporttheseabilitiesinadultsrelatetoWMchangesinchildren.

•  Corticalthicknessmaybeausefulmeasureininvestigatingthisassociation,asage-relatedchangesincorticalthicknessmaysupportimprovementsincognitiveabilitiesasaresultofsynapticpruningandincreasedmyelination(Sowelletal.,2004).

•  However,onlylimitedresearchhasinvestigatedhowcorticalthicknessrelatestoWMabilitiesinchildhood.Forexample,Kharitonovaandcolleagues(2013)foundthatthicknessinsuperiorparietalcortex(SPC),butnotanteriorcingulatecortex(ACC),relatedtoWM.However,SPCdidnotmediatetherelationbetweenageandWM.

•  ThepresentstudyextendsthisresearchbyinvestigatingtherelationbetweenperformanceonadigitspantaskandcorticalthicknessofspeciDicareasrelatedtoWM:ACC,SPC,superiorfrontalcortex(SFC),andmiddlefrontalcortex(MFC).

1.  Desikan,R.,Segonne,F.,Fischl,B.,Quinn,B.,Dickerson,B.,Blacker,D…Killiany,R.(2006).AnautomatedlabelingsystemforsubdividingthehumancerebralcortexonMRIscansintogyralbasedregionsofinterest.Neuroimage,31(3),968-80.

2.  Fischl,B.(2012).FreeSurfer.NeuroImage,62,774–781.doi:10.1016/j.neuroimage.2012.01.021.

3.  Gathercole,S.,&Adams,A.(1993).Phonologicalworkingmemoryinveryyoungchildren.DevelopmentalPsychology,29(4),770-78.

4.  Hayes,(2013).Introductiontomediation,moderation,andconditionprocessanalysis:Aregression-basedapproach.NewYork:GuilfordPress.

5.  Kharitonova,M.,Martin,R.,Gabrieli,J.,&Sheridan,M.(2013).Corticalgray-matterthinningisassociatedwithage-relatedimprovementsonexecutivefunctiontasks.DevelopmentalCognitiveNeuroscience,6,61-71.

6.  Sowell,E.R.,Thompson,P.M.,Leonard,C.M.,Welcome,S.E.,&Kan,E.,Toga,A.W.(2004).Longitudinalmappingofcorticalthicknessandbraingrowthinnormalchildren.TheJournalofNeuroscience,24(38),8223-31.

Forquestionsorcomments,[email protected]

Results:Age-CorticalThicknessAssociations

•  AmediationmodelwastestedusingHayes’SPSSProcessmacro(Hayes,2013).Separatemodelswererunwithageasthepredictor,eachROIasthemediator,andDigitSpanScoreasthedependentvariable.SigniGicantmediationwasobservedforthemodelwithACCasthemediator.SpeciGically,therewasasigniGicantindirecteffectofageonDigitSpanScorethroughACCthickness,b=0.008,SE=0.01,CI[0.0019,0.0191].

Age

ROIACCSPCSFCMFC

DigitSpanPerformance

Results:MediationAnalysis

Results:CorticalThickness-WMAssociations

ACC

SFC

AcknowledgementsWewouldliketoacknowledgesupportfromtheNationalScienceFoundationandtheNationalInstitutesofHealth(GrantnumberRO1HD079518-04).

MFC

0

0.2

0.4

0.6

0.8

1

1.2

3 4 5 6 7 8 9 10

DigitSpanScore

Age(yrs)

r(181)=.57,p<.001

Results:Age-DigitSpanAssociations

SPC

ACC

SPC SFCb=-0.05,SE=0.01,p<0.001

b=-0.02,SE=0.008,p=0.008 b=-0.02,SE=0.009,p=0.03

ACCThickness

SPCThickness

SFCThickness

Age

Age

Age

ACC

b=-0.27,SE=0.06,p<0.01

ACCThickness

SFC

b=-0.22,SE=0.07,p=<0.01

SFCThickness

b=-0.24,SE=0.08,pr=-0.21,p=0.004

SPCThickness

SPC MFC

b=-0.26,SE=0.07,pr=-0.17,p=0.03

MFCThickness

DigitSpanScore

DigitSpanScore

DigitSpanScore

DigitSpanScore