Closed-class words in sentence production: Evidence from a modality-specific dissociation.

Classic observations in the field of the neuropsychology of language have established that brain injury can result in the specific disruption of the ability to use words from the closed class (e.g., determiners, auxiliary verbs, prepositions, etc.) while the production of words from the open class is preserved (e.g., nouns, verbs, etc.). In this study, we report the case of a French native speaker who, following a cerebral-vascular accident, presents a dissociation between open- and closed-class words. Importantly, this dissociation is only observed in the written modality of output while oral speech production is by and large normal. Furthermore, the difficulties in writing closed-class words were only observed during sentence production--in spontaneous production or in writing to dictation tasks--but not during single word production. The origin of this deficit is discussed in the context of previously proposed models of sentence production.