Source reconstruction of clinical resting-state EEG reveals differences in power and functional connectivity in children with developmental dyslexia

Developmental dyslexia is a neurodevelopmental disorder characterized by significant difficulties in reading and spelling. Despite lacking routine neuroimaging markers for dyslexia, recent resting-state electroencephalography (EEG) studies have detected atypical functional connectivity (FC) at the sensor-level in children with dyslexia compared to controls. It remains unclear if routine clinical resting-state EEG can be used to detect source-level differences between children with dyslexia and controls. Using retrospective data, we investigated 70 children with dyslexia and 50 typically developing controls. We analyzed 50 seconds of awake resting-state routine clinical EEG, calculating power and two FC metrics after source-reconstruction. Additionally, correlations between power or FC and IQ, reading, and spelling performance were analyzed. Children with dyslexia had a decrease in theta FC in left temporo-parieto-occipital regions and an increase in alpha FC in left fronto-temporo-parietal regions. Decreased theta FC was observed for right parieto-occipital regions and an increase of alpha FC in right inferior fronto-temporal regions. Furthermore, children with dyslexia demonstrated lower power in delta and theta within the left parieto-occipital regions. A sub-analysis indicated that children with dyslexia in 5 ^th -8 ^th school grades exhibit greater alpha FC in left fronto-temporo-parietal regions. Lower scores in spelling showed a positive and significant association to theta power within left parieto-occipital regions in dyslexia. Significant group differences in power and FC in the theta-alpha range suggest abnormal oscillations as pathophysiological signs of dyslexia orthographic, visual attention, and spelling deficits. Our findings indicate the potential of source-reconstructed clinical routine EEG data to inform clinicians about oscillatory alterations in children with dyslexia.