Neuroanatomy of language processing studied with functional MRI.

This article discusses recent data from functional magnetic resonance imaging (FMRI) studies of language. Although preliminary, these data suggest activation of the left prefrontal cortex across a variety of tasks, with less activation of posterior cortical areas known to play a role in language. Potential sources of error in functional imaging studies related to task subtraction techniques are briefly discussed. The semantic decision task used by the author and colleagues, which produces left lateralized activation of both prefrontal and temporoparietal areas, is presented in detail, and the activation pattern observed in these studies is discussed in the context of converging neuropsychological and positron emission tomography data. It is argued that superior temporal responses evoked by listening to speech represent sensory rather than language processes. The data bring into question the classical disconnection model of transcortical aphasia and confirm the participation of left prefrontal areas in comprehension. FMRI shows promise as an alternative to the intracarotid amobarbital test for language dominance.