title: Circadian regulation of human cortical excitability.
abstract: Prolonged wakefulness alters cortical excitability, which is essential for proper brain function and cognition. However, besides prior wakefulness, brain function and cognition are also affected by circadian rhythmicity. Whether the regulation of cognition involves a circadian impact on cortical excitability is unknown. Here, we assessed cortical excitability from scalp electroencephalography (EEG) responses to transcranial magnetic stimulation in 22 participants during 29 h of wakefulness under constant conditions. Data reveal robust circadian dynamics of cortical excitability that are strongest in those individuals with highest endocrine markers of circadian amplitude. In addition, the time course of cortical excitability correlates with changes in EEG synchronization and cognitive performance. These results demonstrate that the crucial factor for cortical excitability, and basic brain function in general, is the balance between circadian rhythmicity and sleep need, rather than sleep homoeostasis alone. These findings have implications for clinical applications such as non-invasive brain stimulation in neurorehabilitation.
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.|Department of Neurology, Centre Hospitalier Universitaire de Liège, Domaine Universitaire du Sart Tilman, Bâtiment B 35, B-4000 Liège, Belgium.
authors.forename: Julien Q M
authors.initials: JQM
authors.lastname: Ly
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: Giulia
authors.initials: G
authors.lastname: Gaggioni
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Chellappa
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: Soterios
authors.initials: S
authors.lastname: Papachilleos
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Brzozowski
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: Chloé
authors.initials: C
authors.lastname: Borsu
authors.affiliation: Department of Biomedical and Clinical Sciences "L.Sacco", Universit degli Studi di Milano, via G. B. Grassi 74, 20157 Milano, Italy.|Fondazione Europea Di Ricerca Biomedica, Ferb Onlus, 16, V. Stresa, 20125 Milano, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Rosanova
authors.affiliation: Department of Biomedical and Clinical Sciences "L.Sacco", Universit degli Studi di Milano, via G. B. Grassi 74, 20157 Milano, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Sarasso
authors.affiliation: Surrey Sleep Research Centre, University of Surrey, Egerton Road, Guildford GU2 7XP, UK.
authors.forename: Benita
authors.initials: B
authors.lastname: Middleton
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Luxen
authors.affiliation: Surrey Sleep Research Centre, University of Surrey, Egerton Road, Guildford GU2 7XP, UK.
authors.forename: Simon N
authors.initials: SN
authors.lastname: Archer
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: Christophe
authors.identifier: http://orcid.org/0000-0002-4990-425X
authors.initials: C
authors.lastname: Phillips
authors.affiliation: Surrey Sleep Research Centre, University of Surrey, Egerton Road, Guildford GU2 7XP, UK.
authors.forename: Derk-Jan
authors.initials: DJ
authors.lastname: Dijk
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.|Department of Neurology, Centre Hospitalier Universitaire de Liège, Domaine Universitaire du Sart Tilman, Bâtiment B 35, B-4000 Liège, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Maquet
authors.affiliation: Department of Biomedical and Clinical Sciences "L.Sacco", Universit degli Studi di Milano, via G. B. Grassi 74, 20157 Milano, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Massimini
authors.affiliation: GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, University of Liège, 8 allée du 6 août, B30, B-4000 Liège, Belgium.|Walloon excellence in life sciences and biotechnology (WELBIO), Avenue de l'Hôpital, 1B 4000 Liège, Belgium.
authors.forename: Gilles
authors.identifier: http://orcid.org/0000-0003-2483-2752
authors.initials: G
authors.lastname: Vandewalle
mesh_terms: D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm; D003071:Cognition; D000071080:Cortical Excitability / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D012890:Sleep / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult