Colateralization of Broca’s area and the visual word form area in left-handers: fMRI evidence  

Oleh:

Haegen, Lise Van der ; Cai, Qing ; Brysbaert, Marc

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: Brain and Language (Full Text) vol. 122 no. 3 (2012), page 171-178.
Topik: Broca’s area; Cerebral lateralization; fMRI; Reading; Speech; Ventral occipito-temporal (vOT) activity; Visual word form area (VWFA)
Fulltext: 122_03_Haegen.pdf (285.82KB)

Isi artikel

Language production has been found to be lateralized in the left hemisphere (LH) for 95% of right-handed people and about 75% of left-handers. The prevalence of atypical right hemispheric (RH) or bilateral lateralization for reading and colateralization of production with word reading laterality has never been tested in a large sample. In this study, we scanned 57 left-handers who had previously been identified as being clearly left (N = 30), bilateral (N = 7) or clearly right (N = 20) dominant for speech on the basis of fMRI activity in the inferior frontal gyrus (pars opercularis/pars triangularis) during a silent word generation task. They were asked to perform a lexical decision task, in which words were contrasted against checkerboards, to test the lateralization of reading in the ventral occipitotemporal region. Lateralization indices for both tasks correlated significantly (r = 0.59). The majority of subjects showed most activity during lexical decision in the hemisphere that was identified as their word production dominant hemisphere. However, more than half of the sample (N = 31) had bilateral activity for the lexical decision task without a clear dominant role for either the LH or RH, and three showed a crossed frontotemporal lateralization pattern. These findings have consequences for neurobiological models relating phonological and orthographic processes, and for lateralization measurements for clinical purposes.

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