title: Acquisition of typical EEG waveforms during fMRI: SSVEP, LRP, and frontal theta.
abstract: Recent work has demonstrated the feasibility of simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Virtually no systematic comparisons between EEG recorded inside and outside the MR scanner have been conducted, and it is unknown if different kinds of frequency mix, topography, and domain-specific processing are uniformly recordable within the scanner environment. The aim of the study was to investigate several typical EEG waveforms in the same subjects inside the magnet during fMRI and outside the MR examination room. We examined whether uniform artifact subtraction allows the extraction of these different EEG waveforms inside the scanner during EPI scanning to the same extent as outside the scanner. Three well-established experiments were conducted, eliciting steady state visual evoked potentials (SSVEP), lateralized readiness potentials (LRP), and frontal theta enhancement induced by mental addition. All waveforms could be extracted from the EEG recorded during fMRI. Substantially no differences in these waveforms of interest were found between gradient-switching and intermediate epochs during fMRI (only the SSVEP-experiment was designed for a comparison of gradient-with intermediate epochs), or between waveforms recorded inside the scanner during EPI scanning and outside the MR examination room (all experiments). However, non-specific amplitude differences were found between inside and outside recorded EEG at lateral electrodes, which were not in any interaction with the effects of interest. The source of these differences requires further exploration. The high concordance of activation patterns with published results demonstrates that EPI-images could be acquired during EEG recording without significant distortion.
authors.affiliation: Bender Institute of Neuroimaging, University of Giessen, Otto-Behaghel-Str. 10F, D-35394 Giessen, Germany. Gebhard.Sammer@psychol.uni-giessen.de
authors.forename: Gebhard
authors.initials: G
authors.lastname: Sammer
authors.forename: Carlo
authors.initials: C
authors.lastname: Blecker
authors.forename: Helge
authors.initials: H
authors.lastname: Gebhardt
authors.forename: Peter
authors.initials: P
authors.lastname: Kirsch
authors.forename: Rudolf
authors.initials: R
authors.lastname: Stark
authors.forename: Dieter
authors.initials: D
authors.lastname: Vaitl
mesh_terms: D000328:Adult; D016477:Artifacts; D001921:Brain / Q000502:physiology; D003265:Contingent Negative Variation / Q000502:physiology*; D003627:Data Interpretation, Statistical; D004569:Electroencephalography / Q000706:statistics & numerical data*; D005071:Evoked Potentials / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008606:Mental Processes / Q000502:physiology; D008953:Models, Anatomic; D013826:Theta Rhythm