title: How ongoing neuronal oscillations account for evoked fMRI variability.
abstract: Variability of evoked single-trial responses despite constant input or task is a feature of large-scale brain signals recorded by fMRI. Initial evidence signified relevance of fMRI signal variability for perception and behavior. Yet the underlying intrinsic neuronal sources have not been previously substantiated. Here, we address this issue using simultaneous EEG-fMRI and real-time classification of ongoing alpha-rhythm states triggering visual stimulation in human subjects. We investigated whether spontaneous neuronal oscillations-as reflected in the posterior alpha rhythm-account for variability of evoked fMRI responses. Based on previous work, we specifically hypothesized linear superposition of fMRI activity related to fluctuations of ongoing alpha rhythm and a visually evoked fMRI response. We observed that spontaneous alpha-rhythm power fluctuations largely explain evoked fMRI response variance in extrastriate, thalamic, and cerebellar areas. For extrastriate areas, we confirmed the linear superposition hypothesis. We hence linked evoked fMRI response variability to an intrinsic rhythm's power fluctuations. These findings contribute to our conceptual understanding of how brain rhythms can account for trial-by-trial variability in stimulus processing.
authors.affiliation: Bernstein Center for Computational Neuroscience Berlin and Bernstein Focus State Dependencies of Learning, Department of Neurology, Charité Universitaetsmedizin Berlin, Berlin, Germany. robert.becker@charite.de
authors.forename: Robert
authors.initials: R
authors.lastname: Becker
authors.forename: Matthias
authors.initials: M
authors.lastname: Reinacher
authors.forename: Frank
authors.initials: F
authors.lastname: Freyer
authors.forename: Arno
authors.initials: A
authors.lastname: Villringer
authors.forename: Petra
authors.initials: P
authors.lastname: Ritter
mesh_terms: D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology*; D001288:Attention / Q000502:physiology; D001921:Brain / Q000098:blood supply* / Q000166:cytology / Q000502:physiology*; D001931:Brain Mapping; D016009:Chi-Square Distribution; D004569:Electroencephalography / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D013223:Statistics as Topic; D013997:Time Factors; D055815:Young Adult
chemical_list: D010100:Oxygen