Neural source/sink phase connectivity in developmental dyslexia by means of interchannel causality
This work addresses the diagnosis of developmental dyslexia by providing a method to analyze causal brain connectivity, though it is incremental as it builds on existing temporal sampling frameworks.
The study tackled the problem of understanding cause-effect relationships in brain connectivity for developmental dyslexia by analyzing EEG signals with a novel directional connectivity method, finding that anomalies are more pronounced in sink scenarios and achieving classification accuracies of 0.84-0.88 and AUCs of 0.87-0.93.
While the brain connectivity network can inform the understanding and diagnosis of developmental dyslexia, its cause-effect relationships have not yet enough been examined. Employing electroencephalography signals and band-limited white noise stimulus at 4.8 Hz (prosodic-syllabic frequency), we measure the phase Granger causalities among channels to identify differences between dyslexic learners and controls, thereby proposing a method to calculate directional connectivity. As causal relationships run in both directions, we explore three scenarios, namely channels' activity as sources, as sinks, and in total. Our proposed method can be used for both classification and exploratory analysis. In all scenarios, we find confirmation of the established right-lateralized Theta sampling network anomaly, in line with the temporal sampling framework's assumption of oscillatory differences in the Theta and Gamma bands. Further, we show that this anomaly primarily occurs in the causal relationships of channels acting as sinks, where it is significantly more pronounced than when only total activity is observed. In the sink scenario, our classifier obtains 0.84 and 0.88 accuracy and 0.87 and 0.93 AUC for the Theta and Gamma bands, respectively.