Article

In transparent orthographies, like German, children with developmental dyslexia
(DD) are mainly characterized by a reading fluency deficit. The reading fluency
deficit might be traced back to a scarce integration of orthographic and
phonological representations. In order to address this question, the present
study used EEG to investigate the N300, an ERP component which has been
associated with the integration of orthographic and phonological representations.
Twenty children without DD and 18 children with DD performed a phonological
(P)-orthographic (O) matching task (P-O condition), which tapped the integration
of orthographic and phonological representations. A control task was applied
which did not require the integration of orthographic and phonological
representations and consisted only of orthographic information (O-O condition).
The O-O condition revealed a similar N300 distribution between groups with a
bilateral activity over fronto-temporal electrodes. However, in the P-O condition
N300 differentiated the 2 groups of children. The control group revealed greater
activity over left fronto-temporal electrodes, whereas the N300 was distributed
bilaterally in the group of children with DD suggesting deficient integration of
orthographic and phonological representations. These findings might be related to
the reading fluency deficit as it was also observed that better reading fluency
was correlated with higher (r=-.36) and earlier peaking (r=-.33) N300 amplitudes
in the left hemisphere and attenuated N300 amplitudes (r=.45) in the right
hemisphere. Standardized low-resolution electromagnetic tomography analysis
(sLORETA) revealed that children with DD rely more on right temporo-parietal
brain areas compared to children without DD. Furthermore, in order to rule out
that earlier deficient processes might influence the group differences found in
the N300, we analyzed the N170 for group differences. We did not find significant
differences between children without DD and children with DD. In conclusion the
results suggest deficient integration of orthographic and phonological
representations in dyslexia, as indexed by the N300, and further highlight how
this activity is relevant for fluent reading.
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Langue : ANGLAIS