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dc.contributor.authorOrban, Csaba
dc.contributor.authorKong, Ru
dc.contributor.authorLi, Jingwei
dc.contributor.authorChee, Michael WL
dc.contributor.authorYeo, BT Thomas
dc.date.accessioned2020-02-19T11:33:47Z
dc.date.available2020-02-19T11:33:47Z
dc.date.issued2020-02
dc.date.submitted2019-05-23
dc.identifier.issn1544-9173
dc.identifier.otherpbiology-d-19-01472
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/302383
dc.description.abstractThe brain exhibits substantial diurnal variation in physiology and function, but neuroscience studies rarely report or consider the effects of time of day. Here, we examined variation in resting-state functional MRI (fMRI) in around 900 individuals scanned between 8 AM and 10 PM on two different days. Multiple studies across animals and humans have demonstrated that the brain's global signal (GS) amplitude (henceforth referred to as "fluctuation") increases with decreased arousal. Thus, in accord with known circadian variation in arousal, we hypothesised that GS fluctuation would be lowest in the morning, increase in the midafternoon, and dip in the early evening. Instead, we observed a cumulative decrease in GS fluctuation as the day progressed. Although respiratory variation also decreased with time of day, control analyses suggested that this did not account for the reduction in GS fluctuation. Finally, time of day was associated with marked decreases in resting-state functional connectivity across the whole brain. The magnitude of decrease was significantly stronger than associations between functional connectivity and behaviour (e.g., fluid intelligence). These findings reveal time of day effects on global brain activity that are not easily explained by expected arousal state or physiological artefacts. We conclude by discussing potential mechanisms for the observed diurnal variation in resting brain activity and the importance of accounting for time of day in future studies.
dc.languageen
dc.publisherPublic Library of Science (PLoS)
dc.rightsAttribution 4.0 International (CC BY 4.0)
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectResearch Article
dc.subjectBiology and life sciences
dc.subjectMedicine and health sciences
dc.subjectResearch and analysis methods
dc.subjectSocial sciences
dc.subjectPhysical sciences
dc.subjectComputer and information sciences
dc.subjectEngineering and technology
dc.titleTime of day is associated with paradoxical reductions in global signal fluctuation and functional connectivity.
dc.typeArticle
dc.date.updated2020-02-19T11:33:45Z
prism.issueIdentifier2
prism.publicationNamePLoS Biol
prism.volume18
dc.identifier.doi10.17863/CAM.49455
dcterms.dateAccepted2020-01-15
rioxxterms.versionofrecord10.1371/journal.pbio.3000602
rioxxterms.versionVoR
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/
datacite.contributor.supervisoreditor: Seymour, Ben
dc.contributor.orcidOrban, Csaba [0000-0001-9133-3561]
dc.contributor.orcidKong, Ru [0000-0001-7842-0329]
dc.contributor.orcidLi, Jingwei [0000-0002-6395-8801]
dc.contributor.orcidChee, Michael WL [0000-0002-6087-0548]
dc.contributor.orcidYeo, BT Thomas [0000-0002-0119-3276]
dc.identifier.eissn1545-7885
pubs.funder-project-idNational University of Singapore (DPRT/944/09/14)
pubs.funder-project-idNational University of Singapore (R185000271720)
pubs.funder-project-idNational Medical Research Council (CBRG/0088/2015)
pubs.funder-project-idNational University of Singapore (Young Investigator Award)
pubs.funder-project-idNational Research Foundation Singapore (Fellowship (Class of 2017))
pubs.funder-project-idMinistry of Education - Singapore (MOE2014-T2-2-016)
cam.issuedOnline2020-02-18


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Attribution 4.0 International (CC BY 4.0)
Except where otherwise noted, this item's licence is described as Attribution 4.0 International (CC BY 4.0)