title: Tracking reorganization of large-scale effective connectivity in aphasia following right hemisphere stroke.
abstract: In this paper we demonstrate the application of new effective connectivity analyses to characterize changing patterns of task-related directed interaction in large (25-55 node) cortical networks following the onset of aphasia. The subject was a left-handed woman who became aphasic following a right-hemisphere stroke. She was tested on an auditory word-picture verification task administered one and seven months after the onset of aphasia. MEG/EEG and anatomical MRI data were used to create high spatiotemporal resolution estimates of task-related cortical activity. Effective connectivity analyses of those data showed a reduction of bilateral network influences on preserved right-hemisphere structures, and an increase in intra-hemispheric left-hemisphere influences. She developed a connectivity pattern that was more left lateralized than that of right-handed control subjects. Her emergent left hemisphere network showed a combination of increased functional subdivision of perisylvian language areas and recruitment of medial structures.
authors.affiliation: Neuropsychology Laboratory, Massachusetts General Hospital, 175 Cambridge St., CPZ S340, Boston, MA 02114, United States; Department of Psychology, Salem State University, 352 Lafayette St., Salem, MA 01970, United States; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth St., S2301, Charlestown, MA 02129, United States; Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Ave., E25-519, Cambridge, MA 02139, United States. Electronic address: gow@helix.mgh.harvard.edu.
authors.forename: David W
authors.initials: DW
authors.lastname: Gow
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth St., S2301, Charlestown, MA 02129, United States.
authors.forename: Seppo P
authors.initials: SP
authors.lastname: Ahlfors
mesh_terms: D001037:Aphasia / Q000209:etiology* / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008875:Middle Aged; D020127:Recovery of Function; D020521:Stroke / Q000150:complications* / Q000503:physiopathology*
keywords: Aphasia; Effective connectivity; Granger causation; Left-handed; MEG; Recovery; Right hemisphere