MIGRAINE-RELATED CORTICAL ACTIVITY DIFFERENCES DURING AUDIOVISUAL ASSOCIATIVE LEARNING​

Previous studies reported impaired performance of migraine patients on the original visual Rutgers Acquired Equivalence Test (RAET). However, in its audiovisual adaptation (SoundFace task), patients outperformed healthy controls. The present study aimed to characterize cortical activity differences underlying audiovisual associative learning in adults with migraine.
EEG was recorded from 18 interictal migraine patients and 18 matched healthy controls using a 64-channel BioSemi system during the SoundFace task. Data were preprocessed using filters and ICA with ICLabel-assisted artifact rejection, and epoched relative to stimulus onset (–500 to +500 ms). Baseline-normalized power spectral density was estimated in the θ, α, β, and γ frequency bands. Group differences across task phases and time windows were assessed using cluster-based permutation statistics. Time–frequency representations of significant sensor clusters were examined using Morlet wavelet decomposition, and phase-based functional connectivity was quantified with weighted Phase Lag Index (wPLI).
Cluster-based analysis revealed significantly reduced post-stimulus beta-band power over right parieto-occipital and bilateral centro-parietal regions in the migraine group during the learning phase of the task. Time–frequency analysis confirmed reduced low-beta activity in the same post-event interval. Additionally, increased low-theta (4–6 Hz) phase synchronization was observed between left frontal and parietal regions, as well as between bilateral prefrontal regions.
These findings suggest altered cortical activity and connectivity during audiovisual associative learning in migraine. Increased cortical synchronization may support superior performance of migraine patients in audiovisual acquired equivalence learning, while decreased cortical beta-band activity does not exclude the involvement of subcortical compensatory mechanisms.