1-A-D-22. Sleep stages affect the occurrence of high frequency oscillations (HFOs) differently between hippocampus and neocortical areas. Issue 6 (June 2015)

• Record Type: Journal Article
• Authors: Iwasaki, Masaki; Sakuraba, Rie; Okumura, Eiichi; Jin, Kazutaka; Kakisaka, Yosuke; Kato, Kazuhiro; Nakasato, Nobukazu; Tominaga, Teiji
• Is Part Of: Clinical neurophysiology. Volume 126:Issue 6(2015:Jun.)
• Page Start: e56
• Publication Date: 2015-06
• Subjects: Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2015.02.025
• Languages: English
• ISSNs: 1388-2457

Abstract

Abstract : This study was aimed to reveal that influence of sleep stages on the occurrence of HFOs was different between anatomical areas. Nine patients underwent extraoperative intracranial EEG monitoring from both hippocampal depth and neocortical subdural electrodes. Interictal HFOs were detected semi-automatically on EEGs taken during different sleep stages. The difference in the occurrence rate of HFOs between NREM3 and REM sleep stages was normalized per patient, and compared between hippocampus and neocortical electrodes. Number of electrodes showing HFOs at higher rate than standard range was compared between sleep stages and anatomical sites. Hippocampal electrodes ( n = 57) showed higher rate of HFOs during NREM3 sleep than neocortical electrodes ( n = 638) ( p < 0.01). High rate HFOs were observed in 35 hippocampal electrodes and 69 neocortical electrodes during NREM3 sleep, and 22 hippocampal electrodes and 97 neocortical electrodes during REM sleep ( p < 0.05), suggesting that hippocampal electrodes presented high-rate HFOs during NREM3 sleep. Hippocampus shows relatively frequent HFOs during NREM3 sleep compared with neocortical areas. It is important to take sleep stages into account in detection of HFOs for clinical application.