Does real grammatical class effect in word production exist in isolating languages?

Selective noun or verb deficits in word production observed in some aphasic patients have helped us understand how grammatical knowledge is represented in the brain (e.g., Bi, Han, Shu, & Caramazza, 2007; Caramazza & Hillis, 1991; see reviews in Laiacona & Caramazza, 2004; Shapiro & Caramazza, 2003a). It has been shown that such patients are not a coherent group but are produced by various causes, including conceptual ones and grammatical ones. The majority of the research has been conducted with patients speaking Indo-European languages where one important grammatical aspect of nouns and verbs is that they have different inflectional morphological rules. A series of patients who show disproportionate noun or verb deficits in picture naming tasks have also been found to be more severely impaired in inflectional morphological tasks for that corresponding grammatical class (Laiacona & Caramazza, 2004; Shapiro & Caramazza, 2003b; Shapiro, Shelton, & Caramazza, 2000). These observations have led some researchers to propose that morphological operations for nouns and verbs can be selectively impaired, and such grammatical-class specific morphological impairments would cause differences in noun/verb naming. It has been further assumed that for isolating languages such as Vietnamese and Chinese where nouns and verbs do not undergo morphological changes in any grammatical context, the noun/ verb differences would then either root in the conceptual system or in the word form representations (Shapiro & Caramazza, 2003a). Does noun/verb dissociation with real grammatical basis exist in isolating languages such as Chinese? We here present a Chinese patient showing disproportionate impairments in writing verbs over nouns. The grammatical class effect in his writing is not liketo originate in the conceptual system or the orthographic word form representations, indicating that there might exist a grammatical basis for selective verb deficit that is more general than inflectional morphology.