Horwitz, B. et al. Activation of Broca's area during the production of spoken and signed language: a combined cytoarchitectonic mapping and PET analysis. Neuropsychologia 41, 1868-1876

Language Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bldg. 10, Rm. 6C420, MSC 1591, Bethesda, MD 20892, USA.
Neuropsychologia (Impact Factor: 3.3). 02/2003; 41(14):1868-76. DOI: 10.1016/S0028-3932(03)00125-8
Source: PubMed


Broca's area in the inferior frontal gyrus consists of two cytoarchitectonically defined regions-Brodmann areas (BA) 44 and 45. Combining probabilistic maps of these two areas with functional neuroimaging data obtained using PET, it is shown that BA45, not BA44, is activated by both speech and signing during the production of language narratives in bilingual subjects fluent from early childhood in both American Sign Language (ASL) and English when the generation of complex movements and sounds is taken into account. It is BA44, not BA45, that is activated by the generation of complex articulatory movements of oral/laryngeal or limb musculature. The same patterns of activation are found for oral language production in a group of English speaking monolingual subjects. These findings implicate BA45 as the part of Broca's area that is fundamental to the modality-independent aspects of language generation.

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    • "Consistent with the Braun et al. (2001) results, both sign and speech engaged the left inferior frontal gyrus (Broca's area) indicating a modality-independent role for this region in lexical production. Using probabilistic cytoarchitectonic mapping and data from the Braun et al. (2001) study, Horwitz et al. (2003) reported that BA 45 was engaged during both speaking and signing, but there was no involvement of BA 44, compared to the motor baseline conditions. In addition, there was extensive activation in BA 44, but not in BA 45, for the non-linguistic oral and manual control tasks compared to rest. "
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    • "Recent work utilizing cytoarchitectonic probability maps [72] suggests that area 45 supports lexical selection processes whereas area 44 is more involved in lexical access via the segmental route to reading. A number of studies of signed language processing have reliably found activation in the left IFG which further speaks to the modality independence of Broca’s region [36], [73], [74]. "
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    • "FMRI studies have shown 'activation' of certain brain areas involved in language processing (e.g. Osterhout 1997; Hagoort et al. 1999; Embick et al. 2000; Horwitz et al. 2003; Pulvermüller & Assadollahi 2007), with different levels of language processing identified in specific regions, "
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