title: Heterogeneity of arousals in human sleep: A stereo-electroencephalographic study.
abstract: Wakefulness, non-rapid eye movement (NREM), and rapid eye movement (REM) sleep are characterized by specific brain activities. However, recent experimental findings as well as various clinical conditions (parasomnia, sleep inertia) have revealed the presence of transitional states. Brief intrusions of wakefulness into sleep, namely, arousals, appear as relevant phenomena to characterize how brain commutes from sleep to wakefulness. Using intra-cerebral recordings in 8 drug-resistant epileptic patients, we analyzed electroencephalographic (EEG) activity during spontaneous or nociceptive-induced arousals in NREM and REM sleep. Wavelet spectral analyses were performed to compare EEG signals during arousals, sleep, and wakefulness, simultaneously in the thalamus, and primary, associative, or high-order cortical areas. We observed that 1) thalamic activity during arousals is stereotyped and its spectral composition corresponds to a state in-between wakefulness and sleep; 2) patterns of cortical activity during arousals are heterogeneous, their manifold spectral composition being related to several factors such as sleep stages, cortical areas, arousal modality ("spontaneous" vs nociceptive-induced), and homeostasis; 3) spectral compositions of EEG signals during arousal and wakefulness differ from each other. Thus, stereotyped arousals at the thalamic level seem to be associated with different patterns of cortical arousals due to various regulation factors. These results suggest that the human cortex does not shift from sleep to wake in an abrupt binary way. Arousals may be considered more as different states of the brain than as "short awakenings." This phenomenon may reflect the mechanisms involved in the negotiation between two main contradictory functional necessities, preserving the continuity of sleep, and maintaining the possibility to react.
authors.affiliation: Lyon Neuroscience Research Center, Central Integration of Pain Lab, INSERM, U1028, CNRS, UMR5292, Université Claude Bernard, Bron, F-69677, France; Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Service de Neurologie-Sommeil, 165 chemin du grand Revoyet, 69495 Pierre-Benite, France; Hospices civils de Lyon, Hôpital Neurologique, Unité d'hypnologie, Service de Neurologie fonctionnelle et d'épileptologie, Groupement Hospitalier Est, 59 boulevard Pinel, 69677 Bron, France. Electronic address: laure.peter-derex@chu-lyon.fr.
authors.forename: Laure
authors.initials: L
authors.lastname: Peter-Derex
authors.affiliation: Lyon Neuroscience Research Center, Central Integration of Pain Lab, INSERM, U1028, CNRS, UMR5292, Université Claude Bernard, Bron, F-69677, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Magnin
authors.affiliation: Lyon Neuroscience Research Center, Central Integration of Pain Lab, INSERM, U1028, CNRS, UMR5292, Université Claude Bernard, Bron, F-69677, France; Hospices civils de Lyon, Hôpital Neurologique, Unité d'hypnologie, Service de Neurologie fonctionnelle et d'épileptologie, Groupement Hospitalier Est, 59 boulevard Pinel, 69677 Bron, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Bastuji
mesh_terms: D000328:Adult; D001143:Arousal; D058256:Brain Waves; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D059225:Nociception / Q000502:physiology; D010812:Physical Stimulation; D012890:Sleep; D012895:Sleep, REM; D013788:Thalamus / Q000502:physiology*; D058067:Wavelet Analysis; D055815:Young Adult
keywords: Arousal; Cortex; EEG; Humans; Sleep; Thalamus