# Multiscale intracranial EEG dynamics across sleep–wake states: toward memory-related processing

## TL;DR

This study explores how brain activity during sleep and wakefulness relates to memory processing using intracranial EEG recordings.

## Contribution

The study reveals distinct multiscale neural dynamics across sleep-wake states that may support memory-related brain functions.

## Key findings

- Low-frequency power and long-range correlations increase during N2 and N3 sleep.
- REM sleep and wakefulness show fragmented dynamics with reduced temporal persistence.
- Distinct patterns emerge in medial temporal and frontal regions linked to memory processing.

## Abstract

Sleep is known to support memory consolidation through a complex interplay of neural dynamics across multiple timescales. Using intracranial EEG (iEEG) recordings from patients undergoing clinical monitoring, we characterize spectral activity, neuronal avalanche dynamics, and temporal correlations across sleep-wake states, with a focus on their spatial distribution and potential functional relevance. We observe increased low-frequency power, larger avalanches, and enhanced long-range temporal correlations—quantified via Detrended Fluctuation Analysis—during N2 and N3 sleep. In contrast, REM sleep and wakefulness show reduced temporal persistence and fewer large-scale cascades, suggesting a shift toward more fragmented and flexible dynamics. These signatures vary across cortical regions, with distinctive patterns emerging in medial temporal and frontal areas—regions implicated in memory processing. Rather than providing direct evidence of consolidation, our results point to a functional neural landscape that may favor both stabilization and reconfiguration of internal representations during sleep. Overall, our findings highlight the utility of iEEG in revealing the multiscale spatio-temporal structure of sleep-related brain dynamics, offering insights into the physiological conditions that support memory-related processing.