Functional magnetic resonance imaging (FMRI) was used to identify
candidate language processing areas in the intact human
brain. Language was defined broadly to include both phonological and
lexical-semantic functions and to exclude sensory, motor, and general
executive functions. The language activation task required phonetic
and semantic analysis of aurally presented words and was compared with
a control task involving perceptual analysis of nonlinguistic
sounds. Functional maps of the entire brain were obtained from 30
right-handed subjects. These maps were averaged in standard
stereotaxic space to produce a robust "average activation map" that
proved reliable in a split-half analysis. As predicted from classical
models of language organization based on lesion data, cortical
activation associated with language processing was strongly
lateralized to the left cerebral hemisphere and involved a network of
regions in the frontal, temporal, and parietal lobes. Less consistent
with classical models were (1) the existence of left hemisphere
temporoparietal language areas outside the traditional "Wernicke
area," namely, in the middle temporal, inferior temporal, fusiform,
and angular gyri; (2) extensive left prefrontal language areas outside
the classical "Broca area"; and (3) clear participation of these left
frontal areas in a task emphasizing "receptive" language
functions. Although partly in conflict with the classical model of
language localization, these findings are generally compatible with
reported lesion data and provide additional support for ongoing
efforts to refine and extend the classical model.