title: A large N400 but no BOLD effect--comparing source activations of semantic priming in simultaneous EEG-fMRI.
abstract: Numerous studies have reported neurophysiological effects of semantic priming in electroencephalography (EEG) and in functional magnetic resonance imaging (fMRI). Because of differing methodological constraints, the comparability of the observed effects remains unclear. To directly compare EEG and fMRI effects and neural sources of semantic priming, we conducted a semantic word-picture priming experiment while measuring EEG and fMRI simultaneously. The visually presented primes were pseudowords, words unrelated to the target, semantically related words and the identical names of the target. Distributed source analysis of the event-related potentials (ERPs) successfully revealed a large effect of semantic prime-target relatedness (the N400 effect), which was driven by activations in a left-temporal source region. However, no significantly differing activations between priming conditions were found in the fMRI data. Our results support the notion that, for joint interpretations of existing EEG and fMRI studies of semantic priming, we need to fully appreciate the respective methodological limitations. Second, they show that simultaneous EEG-fMRI, including ERP source localization, is a feasible and promising methodological advancement for the investigation of higher-cognitive processes. Third, they substantiate the finding that, compared to fMRI, ERPs are often more sensitive to subtle cognitive effects.
authors.affiliation: Institute for Psychology, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Geukes
authors.affiliation: Experimental Psychology Lab, Department of Psychology, Carl-von-Ossietzky Universität, Oldenburg, Germany.
authors.forename: René J
authors.initials: RJ
authors.lastname: Huster
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, Medical Faculty, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wollbrink
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, Medical Faculty, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Junghöfer
authors.affiliation: Institute for Psychology, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Pienie
authors.initials: P
authors.lastname: Zwitserlood
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, Medical Faculty, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Dobel
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D015438:Health Behavior; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011930:Reaction Time / Q000502:physiology*; D012660:Semantics; D055815:Young Adult