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.

Cortical and white matter substrates supporting visuospatial working memory

“…However, our mixed model analysis did not have su cient statistical power to detect the effect of development on task-related high-gamma amplitudes, given the participation of only 10 children and substantial variation in the spatial sampling of iEEG signals. To the point, a recent iEEG study, which analyzed 8,251 nonepileptic electrode sites across 114 patients ranging from infancy to adulthood, revealed slightly higher rates of spontaneous high-frequency activity at > 80 Hz in extra-occipital lobe regions in younger children compared to older ones (Sakakura et al, 2023); however, the most pronounced developmental variability in such high-frequency activity occurred during infancy, with minimal changes observed from age nine onwards.…”

How to design optimal brain stimulation to modulate phase-amplitude coupling?

“…Since most of the PAC strength is captured by the first harmonic of ρ f , we only consider its zeroth and first order components parametrised by ρ 0 , ρ 1 , and θ 1 such that ρ f (t) = ρ 0 + 2ρ 1 cos (ω s t + θ 1 ). We show in section 4.4 in the Methods that equation (10) translates to three equations in ρ 0 , ρ 1 , and θ 1 (equations ( 15)-( 17)).…”

“…This will allow us to gain insight into which Fourier coefficients 32 can have a significant impact on PAC. Using the approximation for θ f mentioned in section 2.1.2 in the Results, the time evolution of ρ f is given by equation (10). In the steady-state, solutions with PAC will be periodic with period 2π/ω s .…”

“…This increased PAC is reduced by deep brain stimulation (DBS) [14]. Similarly, alpha (8)(9)(10)(11)(12) gamma PAC is exaggerated in the sensorimotor cortex of patients with essential tremor [15]. As expected from its involvement in memory, theta-gamma PAC is impacted in Alzheimer's disease (AD).…”

“…Most notably, PAC was shown to be implicated in memory and learning, in particular through coupling of the amplitude of the gamma rhythm (50–200 Hz) to the phase of the theta rhythm (4-8 Hz) in the hippocampus [1, 2, 3, 4, 5, 6]. Beyond memory processes, PAC is for example modulated during movement and speech [7], visual attention [8], auditory processing [9], complex cognitive function [10], as well as during development [11].…”