Circadian regulation of human cortical excitability

• Published in: Nature communications 2016-06, Vol.7 (1), p.11828-11828, Article 11828
• Main Authors: Ly, Julien Q. M., Gaggioni, Giulia, Chellappa, Sarah L., Papachilleos, Soterios, Brzozowski, Alexandre, Borsu, Chloé, Rosanova, Mario, Sarasso, Simone, Middleton, Benita, Luxen, André, Archer, Simon N., Phillips, Christophe, Dijk, Derk-Jan, Maquet, Pierre, Massimini, Marcello, Vandewalle, Gilles
• Format: Article
• Language: English
• Subjects: 631/378/1385; 631/378/1385/2640; 631/378/1697/2601; Adolescent; Adult; Circadian Rhythm; Cognition; Cognition & reasoning; Cortical Excitability - physiology; Electroencephalography; Electroencephalography - methods; Human health sciences; Humanities and Social Sciences; Humans; Male; Motor Cortex - physiology; multidisciplinary; Neurologie; Neurology; Science; Science (multidisciplinary); Sciences de la santé humaine; Sleep - physiology; Transcranial Magnetic Stimulation; Wakefulness - physiology; Young Adult
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms11828

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. Cognitive performance is impaired after prolonged wakefulness, yet the contribution of circadian rhythms for proper brain function remains unclear. Here the authors show that cortical excitability measured using TMS exhibits robust circadian dynamics which is correlated with cognitive performance.