Effective connectivity and cortical information flow under visual stimulation in migraine with aura

The study aims to evaluate effective connectivity patterns in EEG rhythms under repetitive visual stimulation in migraine with aura patients, in terms of non linear Granger causality and Transfer Entropy. Fifteen migraine with aura (MWA) and 15 migraine without aura (MWoA) patients were evaluated interictally. All subjects were submitted to high density (65 channels) EEG during visual stimulation by black and white checkerboard gratings with two spatial frequencies (0.5 and 2.0 cpd) at 5 and 10Hz (10 and 20 reversal/s). The same visual stimulation was employed to evaluate BOLD signal changes in 6 MWA and 6 MWoA. MWA patients showed increased non linear Granger causality values in beta band under all types of visual stimulation, and increased information flow toward frontal regions, with respect to MWoA and controls. Our results outline important pathophysiological difference between migraine phenotypes. An increased capacity in cortical connections and transfer information may subtend the perception of aura symptoms, probably favoring the progression of cortical spreading depression.