The modality-specific organization of grammatical categories: evidence from impaired spoken and written sentence production.

We describe the case of a brain-damaged individual whose speech is characterized by difficulty with practically all words except for elements of the closed class vocabulary. In contrast, his written sentence production exhibits a complementary impairment involving the omission of closed class vocabulary items and the relative sparing of nouns. On the basis of these differences we argue: (1) that grammatical categories constitute an organizing parameter of representation and/or processing for each of the independent, modality-specific lexicons, and (2) that these observations contribute to the growing evidence that access to the orthographic and phonological forms of words can occur independently.