Druks, J

Evdokimidis, I

Kasselimis, D

van de Koot, H

Varkanitsa, M

UCL Discovery

STEM-, SPRAAK- ENTAALPATHOLOGIEVol. 18, No. S01, 2013, pp. 153-15632.8310/S01/1813-153c© Groningen University PressSyntactic dependency resolution in Broca’saphasiaMaria Varkanitsa1, Dimitrios Kasselimis2,3, Ioannis Evdokimidis2,Constantin Potagas2, Judit Druks1 & Hans van de Koot11Department of Linguistics, University College London, UK2Neurology Department, University of Athens, Greece3Psychology Department, University of Crete, GreeceIntroductionResearch on sentence comprehension in aphasia has shown that individuals withagrammatic Broca’s aphasia often exhibit a highly selective deﬁcit in processingintra-sentential dependencies; comprehension of sentences that contain ﬁller-gap dependencies (i.e. A’-Movement) is impaired, whereas comprehension ofsentences that contain Binding relations are relatively spared. This dissociationhas been attributed to the fact that there are important syntactic and processingdifferences between the two dependencies (Santi & Grodzinsky, 2007a, 2012).Syntactically, the antecedent of a reﬂexive (John in (1a) is in a theta position,whereas in A’-Movement, the displaced ﬁller (the man, that, in (1b)) is not.(1) a. Mary knows that John1 loves himself1 Bindingb. Mary knows the man1 that1 David pinched t1 MovementOne could therefore hypothesize that the dissociation should be linked topredictability, i.e. whether the dependencies can be identiﬁed at an early stage ofprocessing based on syntactic factors. In A’-Movement, the processor encountersthe ﬁller early on and provides awarning that the reader/hearer should store theDPinmemory and go hunting for a gap (predictable dependency). In Binding no suchcues are available; the dependency becomes evident only when processing reachesthe reﬂexive, which is assigned its anaphoric reference in retrospect (unpredictabledependency). The two dependencies also make different demands on WorkingMemory (WM). A’-Movement puts greater demands on storage processes, butBinding on retrieval processes (Santi & Grodzinsky, 2012).The hypothesis that predictability is the key factor distinguishing A’-Movementfrom Binding makes the further prediction that relations mediated by leftward LFmovement should behave like Binding. This prediction is supported by the ﬁndingthat agrammatic patients perform normally on ambiguous doubly quantiﬁedsentences (e.g. A woman is photographing every child) (Saddy, 1995; Varkanitsaet al., 2012), whose inverse scope reading involves (leftward) Quantiﬁer Raising inthe LF component (May, 1977).The present study investigates whether this asymmetry in predictability effectsbetween overt and covert leftward movement is also manifested in the processing154 VARKANITSA ET AL.of sentences with contrastive foci (CF) by Greek-speaking patients with Broca’saphasia. As shown in (2), Greek provides an appropriate minimal pair, with the CFeither moved or in situ.(2) a. Ti GINEKA1 ﬁlai o adras t1 ohi to koritsi. Moved CFThe WOMAN1 ACC is kissing the manNOM t1 not the girl.‘The WOMAN the man is kissing, not the girl.’b. O andrasNOM ﬁlai ti GINEKAACC ohi to koritsi. In situ CFThe man is kissing the WOMAN not the girl‘The man is kissing the WOMAN, not the girl.’MethodsParticipantsFour chronic Greek-speaking patients with aphasia and four non-brain-damagedindividuals participated in the study. Three patients are also agrammatic, thatis, they exhibited impaired comprehension of movement-derived sentences (i.e.wh-questions and passives) during background testing, whereas comprehensionof simple semantically reversible sentences was well preserved. Patients’ WM wasassessed with the digit span task and the Corsi block-tapping task (forward andbackward). The agrammatic patients demonstrated WM deﬁcits in both tasks,whereas the non-agrammatic patient performed within normal limits.ProcedureParticipants performed a picture-selection task, consisted of two experimentalconditions and two ﬁller conditions. The experimental conditions includedsentences with moved object-CF and sentences with in situ object-CF. Sentenceswith subject-CF and simple transitiveswere used as ﬁllers. Each condition included20 semantically reversible sentences.ResultsPatients’ performance on the picture selection task, presented in Table 1, revealeda dissociation between processing of sentences containing moved CF, as in (2a),and sentences containing in situ CF, as in (2b). The agrammatic patients (i.e. AG,AV, AA) performed signiﬁcantly lower in the condition with displaced object-CFcompared to the condition with in situ object-CF. This dissociation disappears inthe case of the non-agrammatic patient (MD) who performed relatively well onboth conditions. Controls performed at ceiling and, hence, their results won’t bediscussed here.DiscussionThese ﬁndings provide further evidence that predictability and the load it placesonWM is a key factor in Broca’s aphasia. An in situ CFmust undergo LFmovementSYNTACTIC DEPENDENCY RESOLUTION IN BROCA’S APHASIA 155Table 1: Number of correct responses (/total) in the experimental conditionsmoved object-CF in situ object-CFAG 3/20 16/20AV 8/20 14/20AA 15/20 20/20MD 19/20 20/20to the left periphery of the clause so as to take scope over its background. As wasthe case with Quantiﬁer Raising, this covert leftward movement appears spared inBroca’s aphasics. Taken together, these results suggest that the problems with overtmovement are WM-related.This conclusion is further supported by the fact that all the agrammatic patientsthat participated in this study had lesions that include left IFG, whereas inthe non-agrammatic patient left IFG was intact. Recent neuroimaging studiesof non-brain-damaged individuals have shown that the presence of a syntacticdependency is not a sufﬁcient condition for activating left Inferior Frontal Gyrus(IFG). Rather, a predictable displacement, as in movement-derived sentences, isrequired (Santi & Grodzinsky, 2007a, 2007b, 2012). This suggests that Broca’s areahosts a ‘syntactically constrained WM’ (Santi & Grodzinsky, 2012: 830), that is thecomponent of WMwhich is responsible for storage processes.A currently unresolved issue is how the impaired performance on reversiblepassives in Broca’s aphasia should be accounted for. Neuroimaging studies reportactivation in Broca’s area, however the fact that patients’ performance varies widelymay suggest that the manner of Broca’s area involvement is different from A’-Movement (Santi & Grodzinsky, 2012).AcknowledgmentMaria Varkanitsa receives research support from Greek State ScholarshipFoundation (IKY), Alexander Onassis Public Beneﬁt Foundation and A.G LeventisFoundation. Dimitrios Kasselimis is supported by “IRAKLITOS II - University ofCrete” of the Operational Program for Education and Lifelong Learning 2007-2013of the NSRF (2007-2013), co-funded by the European Union (European SocialFund) and National Resources.ReferencesMay, R. C. (1977). The grammar of quantification. MIT.Saddy, J. D. (1995). Variables and Events in the Syntax of Agrammatic Speech. Brain andLanguage, 50(2), 135-150.Santi, A., & Grodzinsky, Y. (2007a). Taxing working memory with syntax: Bihemisphericmodulations. Human Brain Mapping, 28(11), 1089-1097.156 VARKANITSA ET AL.Santi, A., & Grodzinsky, Y. (2007b). Working memory and syntax interact in Broca’s area.NeuroImage, 37(1), 8-17.Santi, A., & Grodzinsky, Y. (2012). Broca’s area and sentence comprehension: A relationshipparasitic on dependency, displacement or predictability? Neuropsychologia, 50(5),821-832.Varkanitsa, M., Kasselimis, D., Potagas, C., Evdokimidis, I., Van de Koot, H., & Druks, J.(2012). Processing of Covert Scope Inversion in Broca’s Aphasia. Procedia - Socialand Behavioral Sciences, 61(0), 277-278.

Syntactic Dependency Resolution in Broca's Aphasia

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Syntactic Dependency Resolution in Broca's Aphasia

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