0094 Oscillatory Theta-Band Activity as a Sleep Stage Independent Measure of REM-like Activity throughout Sleep

Abstract Introduction The importance of human cortical theta-band power during REM is suggested by its association with aspects emotional processing. Currently, this measured first visual-inspection polysomnography to define REM-sleep (scored-REM) and then summing the total theta within. However, activity attributed scored-REM has been hypothesized occur some scored-NREM (“covert REM”) conflates different sources. Oscillatory (OTA) in hippocampus associated regions hallmark REM-like sleep invasive animal studies. We posit that an EEG assessment specifically targeting all-night OTA a more accurate biomarker theta-dependent functions than current methods. As step towards testing hypothesis, we developed stage independent approach isolate from scalp-EEG. For validation, compared measure conventional-staging high-frequency activity. Methods Our method uses Irregular-Resampling Auto-Spectral Analysis remove aperiodic spectrum (a major source power), followed low-band normalization derive relative oscillatory-theta (OTA). Covert REM-containing epochs were calculated based on exceeding threshold. combined data two in-laboratory studies resulting sample size 42 healthy young adult subjects. Analyses used non-sleep restricted overnight recordings frontal channel. Results A clear peak was observed after Using all stages, found separation evidenced conventional staging (OTA: scored-REM>scored-NREM, p=0.003 vs theta: scored-REM<scored-NREM, p<0.001) correlation beta-band r=0.2, p<0.001 p=0.4). Supporting “covert REM”, present (p<0.001). On average single episode, covert 28% scored- NREM (range=2-85%). Conclusion novel automated for measuring activity, This across stages and, as reported companion abstract, test hypothesis constitutes better predictor REM-dependent behavioral effects conventions. Support (If Any) effort fully supported Department Defense Military Operational Medicine Research Program (MOMRP).