Developmental atlas of phase-amplitude coupling between physiologic high-frequency oscillations and slow waves

Abstract

We investigated the developmental changes in high-frequency oscillation (HFO) and Modulation Index (MI) – the coupling measure between HFO and slow-wave phase. We generated normative brain atlases, using subdural EEG signals from 8251 nonepileptic electrode sites in 114 patients (ages 1.0–41.5 years) who achieved seizure control following resective epilepsy surgery. We observed a higher MI in the occipital lobe across all ages, and occipital MI increased notably during early childhood. The cortical areas exhibiting MI co-growth were connected via the vertical occipital fasciculi and posterior callosal fibers. While occipital HFO rate showed no significant age-association, the temporal, frontal, and parietal lobes exhibited an age-inversed HFO rate. Assessment of 1006 seizure onset sites revealed that z-score normalized MI and HFO rate were higher at seizure onset versus nonepileptic electrode sites. We have publicly shared our intracranial EEG data to enable investigators to validate MI and HFO-centric presurgical evaluations to identify the epileptogenic zone.

It remains unclear how cortical high-frequency oscillations (HFOs) and their relation with slow waves change with age. Here, the authors found that while HFO rate widely decreases over time, its coupling with slow waves strengthens in the occipital lobe during childhood.