Word class-specific deficits in Wernicke's aphasia

Lexical impairments were investigated in two patients with Wernicke's aphasia due to lesion of the posterior perisylvian cortex, Content and function words were presented in a lexical decision task. In both patients, processing of function words tended to be more severely impaired than content word processing, Closer examination revealed that word class-specific differences were only significant for stimuli of word frequencies up to 400/Mio, but not for words with very high frequency (>400/Mio). These results are consistent with the view that not only the anterior perisylvian cortex close to Broca's area, but, in addition, posterior perisylvian cortices play an important role in processing grammatical words of moderate word frequency. These results are used to evaluate models of word representation in the brain.