[Analysis of EEG coherence in examination of an automation deficit in reading-spelling disorder--a pilot study]

Do dyslexic children exhibit a general automatizational deficit as well as a phonological deficit?

In 16 children aged 9-11 years the reaction time, the number of mistakes and EEG (19 scalp electrodes) were measured in three experiments (verbal and nonverbal). The EEG data was baseline-corrected and after a fast fourier transformation, analyzed with the coherence tool of the Brainvision Software.

The dyslexic group made more mistakes than the control group on all tasks but their reaction times were significantly longer only on the verbal tasks. There were no coherence differences on the nonverbal task. On the language-dependent tasks the dyslexics showed higher total-frontal and lower left-frontal coherences only in the theta-frequency range, while in the alpha and beta frequency ranges coherences did not differ.

A language-dependent cognitive automatizational deficit in the dyslexic group is assumed that is depicted by the higher synchronization of total-frontal coherences (involvement of the central executive) and is based on the less established functional coupling of cortical subsystems for language processing.