An event-related fMRI study of implicit phrase-level syntactic and semantic processing

Most neuroimaging studies of language function to date use a block-subtract ion paradigm in which images acquired during relatively long periods of tar get stimuli are compared to those acquired during a control period. These s tudies typically require an overt response on the part of the subject, usua lly some type of discrimination or grammatical judgment by button press, or silent word generation. Results from studies of syntactic and semantic pro cessing have generally been compatible with the classical correlation to Br oca's area and Wernicke's area, respectively. Recently, functional magnetic resonance imaging (fMRI) studies departing from the block-subtraction para digm in favor of event-related fMRI paradigms have been reported. We have e xtended the use of this approach to examine implicit (i.e., without an expl icit task on the part of the subject) syntactic and semantic processing at the phrasal level, using visually presented verb phrases. Left BA 44 is mor e strongly activated for the syntactic condition than the semantic conditio n. BA. 45, 10, and 46 show laterality differences: mostly left-lateralized for the syntactic condition and right-lateralized for the semantic conditio n. We also find activations of the inferior parietal lobe, consistent with a visual oddball response reported previously, and the anterior cingulate g yrus (BA 32), implicated for attention and memory-related processes in nume rous studies. (C) 1999 Academic Press.