title: Direction of magnetoencephalography sources associated with feedback and feedforward contributions in a visual object recognition task.
abstract: Identifying inter-area communication in terms of the hierarchical organization of functional brain areas is of considerable interest in human neuroimaging. Previous studies have suggested that the direction of magneto- and electroencephalography (MEG, EEG) source currents depend on the layer-specific input patterns into a cortical area. We examined the direction in MEG source currents in a visual object recognition experiment in which there were specific expectations of activation in the fusiform region being driven by either feedforward or feedback inputs. The source for the early non-specific visual evoked response, presumably corresponding to feedforward driven activity, pointed outward, i.e., away from the white matter. In contrast, the source for the later, object-recognition related signals, expected to be driven by feedback inputs, pointed inward, toward the white matter. Associating specific features of the MEG/EEG source waveforms to feedforward and feedback inputs could provide unique information about the activation patterns within hierarchically organized cortical areas.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02135, USA. Electronic address: seppo@nmr.mgh.harvard.edu.
authors.forename: Seppo P
authors.initials: SP
authors.lastname: Ahlfors
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA; Brown University, Providence, RI, USA.
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Jones
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ahveninen
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02135, USA.
authors.forename: Matti S
authors.initials: MS
authors.lastname: Hämäläinen
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02135, USA.
authors.forename: John W
authors.initials: JW
authors.lastname: Belliveau
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA; Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Bar
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D021641:Recognition, Psychology; D013702:Temporal Lobe / Q000502:physiology; D014796:Visual Perception
keywords: Bottom–up; Cerebral cortex; Current dipole; Magnetoencephalography; Top–down