Verb retrieval and sentence production in aphasia.

This paper presents a subject with a selective verb retrieval deficit. Nouns were produced more successfully than verbs in spontaneous speech, picture naming and when naming to definition. The word class effect was not observed in comprehension tasks, reading aloud or writing. This indicated that it was due to a specific problem in accessing verbs' phonological representations from semantics. The second part of the paper explores the implications of the verb deficit for sentence production. Analyses of narrative speech revealed a typically agrammatic profile, with minimal verb argument structure and few function words and inflections. Two investigations suggested that the sentence deficit was at least partly contingent upon the verb deficit. In the first, the subject was asked to produce a sentence with the aid of a provided noun or verb. The noun cues were not effective in eliciting sentences, whereas verb cues were. The second investigation explored the effects of therapy aiming to improve verb retrieval. This therapy resulted in better verb retrieval and improved sentence production with those verbs. These findings suggest that an inability to access verbs' phonological representations can severely impair sentence formulation. Implications for models of sentence production are considered.