Role of the superior parietal lobules in letter-identity processing within strings: FMRI evidence from skilled and dyslexicreaders
Traditionally, the ventral occipito-temporal (vOT) area, but not the superior parietal lobules (SPLs), is thought as belonging to the neural system of visual word recognition. However, some dyslexic children who exhibit a visual attention span disorder – i.e. poor multi-element parallel processing –...
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Veröffentlicht in: | Neuropsychologia 2013-03, Vol.51 (4), p.601-612 |
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Sprache: | eng |
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Zusammenfassung: | Traditionally, the ventral occipito-temporal (vOT) area, but not the superior parietal lobules (SPLs), is thought as belonging to the neural system of visual word recognition. However, some dyslexic children who exhibit a visual attention span disorder – i.e. poor multi-element parallel processing – further show reduced SPLs activation when engaged in visual multi-element categorization tasks. We investigated whether these parietal regions further contribute to letter-identity processing within strings. Adult skilled readers and dyslexic participants with a visual attention span disorder were administered a letter-string comparison task under fMRI. Dyslexic adults were less accurate than skilled readers to detect letter identity substitutions within strings. In skilled readers, letter identity differs related to enhanced activation of the left vOT. However, specific neural responses were further found in the superior and inferior parietal regions, including the SPLs bilaterally. Two brain regions that are specifically related to substituted letter detection, the left SPL and the left vOT, were less activated in dyslexic participants. These findings suggest that the left SPL, like the left vOT, may contribute to letter string processing.
► Detection of substituted letters within strings is impaired in dyslexic adults. ► This impairment relates to underactivation of the left superior parietal lobule. ► The left ventral occipito-temporal area also is less activated. ► These two brain regions may belong to the same neural network. ► The left superior parietal lobule contributes to visual word recognition. |
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ISSN: | 0028-3932 1873-3514 |
DOI: | 10.1016/j.neuropsychologia.2012.12.010 |