The relation between syntactic and morphological recovery in agrammatic aphasia: A case study

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Abstract
Background: Production of grammatical morphology is typically impaired in agrammatic aphasic individuals, as is their capacity to produce the syntactic structure responsible for licensing that morphology. Whether these two impairments are causally related has been an issue of long‐standing debate. If morphological deficits are a side‐effect of underlying syntactic ones, as has been claimed (Friedmann & Grodzinsky, 1997 Friedmann, N. and Grodzinsky, Y. 1997. Tense and agreement in agrammatic production: Pruning the syntactic tree.. Brain and Language, 56: 397–425. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] ; Izvorski & Ullman, 1999 Izvorski, R. and Ullman, M. 1999. Verb inflection and the hierarchy of functional categories in agrammatic anterior aphasia.. Brain and Language, 69: 288–291. [Google Scholar] ), therapy that improves the syntactic deficit should remediate the morphological deficit as well. This paper reports a case study of one individual with such co‐occurring impairments and describes their recovery in response to linguistically motivated treatment targeting his syntactic deficits. Methods & Procedures: MD is a 56‐year‐old male diagnosed with non‐fluent Broca's aphasia subsequent to a left‐hemisphere CVA, with limited capacity to produce syntactically complex utterances and grammatical morphology. He was enrolled in therapy using Treatment of Underlying Forms (TUF; Thompson & Shapiro, 2005 Thompson, C. K. and Shapiro, L. P. 2005. Treating agrammatic aphasia within a linguistic framework: Treatment of Underlying Forms.. Aphasiology, 19: 1021–1036. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar] ), targeting production of sentences involving Wh‐movement (object relative clauses). MD participated in twice‐weekly treatment sessions for approximately 2 months, with daily probes assessing his production of treated and untreated sentence types. In addition, probes assessing his grammatical morphology and sentence production were administered pre‐ and post‐treatment. Outcomes & Results: Pre‐treatment scores in tests of grammatical morphology and sentence production indicated deficits in both domains. During treatment, MD successfully acquired production of a variety of sentences with Wh‐movement, although this did not generalise to sentences involving a grammatically distinct movement operation (NP‐movement). Post‐treatment scores also indicated a lack of improvement in production of grammatical morphology. Conclusions: The dissociation between MD's morphological and syntactic recovery indicates that the recovery of syntactic and morphological processes in aphasia may occur independently in some individuals. The result would not be predicted by approaches in which morphological and syntactic impairments are strongly and causally related in aphasia, such as the tree‐pruning hypothesis (Friedmann, 2001 Friedmann, N. 2001. Agrammatism and the psychological reality of the syntactic tree.. Journal of Psycholinguistic Research, 30: 71–88. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] ; Friedmann & Grodzinsky, 1997 Friedmann, N. and Grodzinsky, Y. 1997. Tense and agreement in agrammatic production: Pruning the syntactic tree.. Brain and Language, 56: 397–425. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] ). Further, these results reinforce the conclusion that aphasia treatment can lead to generalisation, but only to linguistic material that is in a subset relation to trained structures (Thompson, Shapiro, Kiran, & Sobecks, 2003 Thompson, C. K. , Shapiro, L. P. , Kiran, S. and Sobecks, J. 2003. The role of syntactic complexity in treatment of sentence deficits in agrammatic aphasia: The complexity account of treatment efficacy (CATE).. Journal of Speech, Language, and Hearing Research, 46: 591–607. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] ). This research was supported by the NIH under grant DC‐01948 to C. K. Thompson. The authors are grateful to Audrey Holland and two anonymous reviewers for their exceptionally helpful comments and suggestions. The authors are especially grateful to MD and his family for his participation in this research.