title: Spatiotemporal Signatures of Lexical-Semantic Prediction.
abstract: Although there is broad agreement that top-down expectations can facilitate lexical-semantic processing, the mechanisms driving these effects are still unclear. In particular, while previous electroencephalography (EEG) research has demonstrated a reduction in the N400 response to words in a supportive context, it is often challenging to dissociate facilitation due to bottom-up spreading activation from facilitation due to top-down expectations. The goal of the current study was to specifically determine the cortical areas associated with facilitation due to top-down prediction, using magnetoencephalography (MEG) recordings supplemented by EEG and functional magnetic resonance imaging (fMRI) in a semantic priming paradigm. In order to modulate expectation processes while holding context constant, we manipulated the proportion of related pairs across 2 blocks (10 and 50% related). Event-related potential results demonstrated a larger N400 reduction when a related word was predicted, and MEG source localization of activity in this time-window (350-450 ms) localized the differential responses to left anterior temporal cortex. fMRI data from the same participants support the MEG localization, showing contextual facilitation in left anterior superior temporal gyrus for the high expectation block only. Together, these results provide strong evidence that facilitatory effects of lexical-semantic prediction on the electrophysiological response 350-450 ms postonset reflect modulation of activity in left anterior temporal cortex.
authors.affiliation: Department of Psychiatry, Harvard Medical School and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Department of Linguistics, University of Maryland, College Park, MD 20742, USA Department of Psychology, Tufts University, Medford, MA 02155, USA.
authors.forename: Ellen F
authors.initials: EF
authors.lastname: Lau
authors.affiliation: Department of Psychiatry, Harvard Medical School and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Department of Psychology, Tufts University, Medford, MA 02155, USA.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Weber
authors.affiliation: Department of Radiology, Harvard Medical School and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Department of Signal and Image Processing, Institut Mines-Télécom, Télécom ParisTech, CNRS LTCI, Paris, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Gramfort
authors.affiliation: Department of Radiology, Harvard Medical School and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Division of Health Sciences and Technology, Harvard-Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Matti S
authors.initials: MS
authors.lastname: Hämäläinen
authors.affiliation: Department of Psychiatry, Harvard Medical School and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Department of Psychology, Tufts University, Medford, MA 02155, USA.
authors.forename: Gina R
authors.initials: GR
authors.lastname: Kuperberg
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D011932:Reading; D012660:Semantics; D012815:Signal Processing, Computer-Assisted; D013702:Temporal Lobe / Q000502:physiology*; D055815:Young Adult
keywords: N400; anterior temporal cortex; expectation; magnetoencephalography; semantic