title: Distinctive time-lagged resting-state networks revealed by simultaneous EEG-fMRI.
abstract: Functional activation as evidenced by blood oxygen level-dependent (BOLD) functional MRI changes or event-related EEG is known to closely follow patterns of stimulation or self-paced action. Any lags are compatible with axonal conduction velocities and neural integration times. The important analysis of resting state networks is generally based on the assumption that these principles also hold for spontaneous fluctuations in brain activity. Previous observations using simultaneous EEG and fMRI indicate that slower processes, with delays in the seconds range, determine at least part of the relationship between spontaneous EEG and fMRI. To assess this relationship systematically, we used deconvolution analysis of EEG-fMRI during the resting state, assessing the relationship between EEG frequency bands and fMRI BOLD across the whole brain while allowing for time lags of up to 10.5s. Cluster analysis, identifying similar BOLD time courses in relation to EEG band power peaks, showed a clear segregation of functional subsystems of the brain. Our analysis shows that fMRI BOLD increases commonly precede EEG power increases by seconds. Most zero-lag correlations, on the other hand, were negative. This indicates two main distinct neuromodulatory mechanisms: an "idling" mechanism of simultaneous electric and metabolic network anticorrelation and a "regulatory" mechanism in which metabolic network activity precedes increased EEG power by some seconds. This has to be taken into consideration in further studies which address the causal and functional relationship of metabolic and electric brain activity patterns.
authors.affiliation: Department of Clinical Psychology and Psychophysiology, Center for Mental Health, Freiburg University Medical Center, Hauptstraße 5, 79104 Freiburg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Feige
authors.affiliation: Department of Clinical Psychology and Psychophysiology, Center for Mental Health, Freiburg University Medical Center, Hauptstraße 5, 79104 Freiburg, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Spiegelhalder
authors.affiliation: Department of Clinical Psychology and Psychophysiology, Center for Mental Health, Freiburg University Medical Center, Hauptstraße 5, 79104 Freiburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kiemen
authors.affiliation: Psychiatric Hospital, University of Zürich, Lenggstrasse 31, 8032 Zürich, Switzerland.
authors.forename: Oliver G
authors.initials: OG
authors.lastname: Bosch
authors.affiliation: Section for Experimental Neuropsychiatry, Center for Mental Disorders, Freiburg University Medical Center, Hauptstraße 5, 79104 Freiburg, Germany.
authors.forename: Ludger
authors.initials: L
authors.lastname: Tebartz van Elst
authors.affiliation: Department of Radiology, Section of Medical Physics, University Medical Center Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.affiliation: Psychiatric Hospital, University of Zürich, Lenggstrasse 31, 8032 Zürich, Switzerland.
authors.forename: Erich
authors.initials: E
authors.lastname: Seifritz
authors.affiliation: Department of Clinical Psychology and Psychophysiology, Center for Mental Health, Freiburg University Medical Center, Hauptstraße 5, 79104 Freiburg, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Riemann
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D058256:Brain Waves / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000502:physiology*; D007319:Sleep Initiation and Maintenance Disorders / Q000000981:diagnostic imaging*; D013997:Time Factors
keywords: EEG frequency bands; EEG-fMRI; Insomnia; Resting state; Spontaneous activity