Impairments in spoken language are among the most common sequelae of brain damage due to stroke, trauma or neurodegenerative disease. Occasionally, patients with aphasia present with selective difficulties producing words of one grammatical category. Damage to the left prefrontal cortex tends to result in a deficit in verb production; left temporal damage often results in greater difficulty with nouns. However, the nature of these deficits remains controversial: Do they result from problems in representing meaning (semantics), retrieving words (lexical access), or using words in the grammatical context of sentences (morphosyntax)? Are the causes of putative noun-verb differences heterogeneous across patients? I propose to screen aphasic patients for grammatical category specific deficits and to evaluate the potential causes of these deficits using tasks that specifically probe semantic, lexical and morphosyntactic processing, with attention to variations in lesion patterns that may correlate with distinct behavioral deficits. In parallel, I will conduct studies using functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (rTMS) to probe the cortical correlates of noun and verb processing in unimpaired subjects performing similar tasks. ? ?
| Cappelletti, Marinella; Fregni, Felipe; Shapiro, Kevin et al. (2008) Processing nouns and verbs in the left frontal cortex: a transcranial magnetic stimulation study. J Cogn Neurosci 20:707-20 |
| Shapiro, Kevin A; Moo, Lauren R; Caramazza, Alfonso (2006) Cortical signatures of noun and verb production. Proc Natl Acad Sci U S A 103:1644-9 |
