Bilingualsconstantlyexerciselanguagecontrol,aformofcognitivecontrol,bysuccessfullymanaging activationoftwolanguages,switchingbetweenthematwill,whileavoidingswitchingbymistake.Both languageandcognitivecontrolmaydeclineinaging,andagrowingbodyofevidencesuggeststhatstandard approachestoneuropsychologicalassessmentofbilingualscanresultininaccuratediagnoses.Aprominent theorysuggeststhatbilingualsrelyoninhibitiontoachieveefficientlanguagecontrol.Considerabledata supportthisclaiminspeechproductionandinyoungbilinguals,butlimitedresearchcharacterizestheroleof inhibitioninbilinguallanguagecomprehension,andhowinhibitorycontrolmechanismsmaychangeinaging bilinguals.Wehypothesizethatbilingualsrelyoninhibitionbroadly,inbothmodalities,andthatdomaingeneral inhibition,whichdeclinesinaging,underliesbilinguallanguagecontrol.Studiestodatemayhavefailedto revealinhibitorycontrolmechanismsbyuseofrelativelysimpletasks,measureswithlimitedsensitivity,and paradigmsthatdonoteffectivelyelicitinhibitorycontrol.Mostresearchonbilinguallanguagecontrolhas focusedonbehavioralresponsesinyoungbilingualsproducingout-of-context(e.g.,singlepicturenaming)or limitedcontextspeech(e.g.,singlesentences).
In Aim1, weexaminetheneuralcorrelatesofbilingual paragraphreading,toexaminethepossibleroleofinhibitionindefaultlanguageselectionduring comprehensionofshortstorieswithlanguageswitches,ataskthatresemblesnaturalisticlanguage comprehensionmorethanpreviouslystudiedtasks.WehypothesizefMRIwillrevealactivationofbrainregions commonlyassociatedwithinhibition(DLPFC,ACC)inaconditionthatrequiresbilingualstoselectthe nondominantlanguageasdefaultwhenprocessingoccasionalswitchestothedominantlanguage,andpredict changesinactivationinyoungversusolderbilinguals,whosebrainswillneedtocompensateforinefficiencyof inhibitorycontrolmechanisms.
In Aim2, weexaminepossibleoverlapbetweenlanguageandcognitivecontrol byinvestigatingthepossibilityofaging-relateddeclineinapowerfulbehavioralsignatureofinhibitorycontrol, i.e.,fullyreversedlanguagedominanceeffects,usingaversionofthecuedpicture-namingtaskthatwe recentlyidentifiedtoconsistentlyexhibitreverseddominanceeffectswithrepetition.Wehypothesizethistask willrevealaging-relateddeclineinabilitytoinhibitthedominantlanguage.Theproposedstudieswillexamine theintersectionofbilinguallanguageprocessingandagingtodeveloptheoreticalmodelsofcognitive processinginbilinguals,andtoincreaseinformationabouthowbilingualismaffectscognitivetestperformance, whichisnecessaryforearlyidentificationofcognitiveimpairmentwiththegoalofdelaying,slowing,orpossibly reversingcognitivedeclineinaginganddementia.Finally,thisresearchprojectwillenhancetheapplicant?s graduateschooltrainingandwillleadtoasuccessfulcareerasaneuropsychologisttrainedinimagingand agingresearch,withaspecialfocusonbilingualismwhichisoftencorrelatedwithminoritystatusintheUSA.
Understandingthepatternsofcognitiveaging,whichappeartobedifferentinbilingualindividuals,isimportant forimprovingcognitiveassessmentofthegrowingnumberofagingbilingualsandforeventuallyslowing, delaying,orreversingcognitivedecline.Accordingtosomeaccounts,inhibitorycontrol?ortheabilityto preventirrelevantinformationfromdetractingfromcognitiveperformance?declineswithageandmayalso impactbilinguals?abilitytoeffectivelycontrolactivationoftheirtwolanguages.Theproposedresearchwill advancepublichealthgoalsbyelucidatingtheneuralandcognitivemechanismsofage-relateddeclinein inhibitorycontrol,andhowthisdeclinemayaffectlanguageperformanceofbilingualindividuals.
