This study examined the relationship between verb retrieval and verb-argument-structure properties in seven agrammatic aphasic patients using tasks requiring access to the verb's lexicon for both comprehension-and production like processes. Results showed intact comprehension of both nouns and verbs and noun naming, but impaired naming of verbs. Subjects also demonstrated near-normal performance on a grammaticality judgment task involving verb-argument-structure violations but were impaired in categorizing verbs by type (based on number of obligatory arguments). In both naming and categorization conditions, a hierarchy of verb difficulty emerged. Subjects were more accurate in naming/categorizing one-place verbs than two-place verbs and more accurate in naming/categorizing two-place verbs than three-place verbs. The pattern of selective impairment in lexical access/retrieval supports the hypothesis that one dimension of normal lexical organization is by form class. The results also suggest that no necessary relationship exists between production difficulties and comprehension of nouns/verbs in agrammatism. Further, the performance pattern noted supports the claim that verb-argumentstructure properties, an important component of the verb lexicon, influence verb production at the single-word and at the sentence level. Subjects' performance on different tasks suggests that the locus of breakdown in the verb-retrieval processes for production like tasks may be in accessing information at the lemma level of representation as per Bock's model (1995) of sentence production.
Keywordsverb production in aphasia; verb categorization in aphasia; verb argument structure in aphasia; agrammatism; lexical organization in aphasia Comprehension and production of nouns and verbs have been studied in several neurological populations including aphasic patients. Researchers investigating production of nouns and verbs in aphasic patients have reported dissociations between these word classes
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Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript (Berndt, Mitchum, Haendiges, & Sandson, 1997;Miceli, Silveri, Nocentini, & Caramazza, 1988;Miceli, Silveri, Villa, & Caramazza, 1984; Zingeser & Berndt, 1990). Agrammatic aphasic patients show more difficulty naming verbs than nouns, while anomic aphasic subjects show the opposite pattern, suggesting that selective impairment in lexical representation and/or the lexical retrieval process can occur along the form class category. Miceli et al.'s (1988) Italian-speaking agrammatic aphasic subjects also showed such dissociations in comprehension, but this finding has not held up across studies (Berndt et al., 1997); most studies have shown a selective deficit in verb production, with comprehension remaining relatively unimpaired.Similar patterns also have been reported in studies examining sentence processing and production with a focus on verb-argument structure. Data from sentence comprehension studies indicate that agrammatic aphasic subjects show in...