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Abstract:
Abstract: The neurological bases of language processing are
incompletely understood. Several neuroimaging studies have reported
localized brain activation for different aspects of auditory
language processing, including semantic, and phonological
processing (e.g. Peterson et al., 1988; Price et al., 1996; Zatorre
et al., 1992). In this study, we focussed on the fundamental
question of whether different brain areas are involved in the
processing of speech vs. non-speech auditory stimuli. Whereas
previous studies investigating this question compared words to
simple non-speech foils such as tones (e.g. Binder et al., 1996) or
noise bursts (Zatorre et al., 1992), we compared processing of a
single isolated nonsense word (speech) to processing of
acoustically complex 3-formant sine-wave counterparts (non-speech)
using an event-related fMRI design. As in these studies, we
observed differential activation to speech stimuli compared to
non-speech counterparts, revealing a high degree of specificity in
the neural processing of speech. Patterns of activation included
bilateral middle temporal gyrus and left inferior frontal gyrus,
consistent with previous reports of language-specific activation in
the temporal (e.g. Price et al., 1992) and inferior frontal lobes
(e.g. Chee et al., 1999) in more sophisticated linguistic tasks.
Engagement of these language areas in processing even single
isolated words suggests a potential readiness triggered by
linguistic stimuli, preparing the brain for further linguistic
analysis.
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