  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.
