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Distributed source modeling of language with magnetoencephalography: Application to patients with intractable epilepsy
Author(s) -
McDonald Carrie R.,
Thesen Thomas,
Hagler Jr Donald J.,
Carlson Chad,
Devinksy Orrin,
Kuzniecky Rubin,
Barr William,
Gharapetian Lusineh,
Trongnetrpunya Amy,
Dale Anders M.,
Halgren Eric
Publication year - 2009
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1167.2009.02172.x
Subject(s) - magnetoencephalography , laterality , statistical parametric mapping , epilepsy , temporal lobe , psychology , frontal lobe , occipital lobe , lateralization of brain function , temporal cortex , audiology , neuroscience , electroencephalography , medicine , magnetic resonance imaging , radiology
Summary Purpose: To examine distributed patterns of language processing in healthy controls and patients with epilepsy using magnetoencephalography (MEG), and to evaluate the concordance between laterality of distributed MEG sources and language laterality as determined by the intracarotid amobarbital procedure (IAP). Methods: MEG was performed in 10 healthy controls using an anatomically constrained, noise‐normalized distributed source solution (dynamic statistical parametric map, dSPM). Distributed source modeling of language was then applied to eight patients with intractable epilepsy. Average source strengths within temporoparietal and frontal lobe regions of interest (ROIs) were calculated, and the laterality of activity within ROIs during discrete time windows was compared to results from the IAP. Results: In healthy controls, dSPM revealed activity in visual cortex bilaterally from ∼80 to 120 ms in response to novel words and sensory control stimuli (i.e., false fonts). Activity then spread to fusiform cortex ∼160–200 ms, and was dominated by left hemisphere activity in response to novel words. From ∼240 to 450 ms, novel words produced activity that was left‐lateralized in frontal and temporal lobe regions, including anterior and inferior temporal, temporal pole, and pars opercularis, as well as bilaterally in posterior superior temporal cortex. Analysis of patient data with dSPM demonstrated that from 350 to 450 ms, laterality of temporoparietal sources agreed with the IAP 75% of the time, whereas laterality of frontal MEG sources agreed with the IAP in all eight patients. Discussion: Our results reveal that dSPM can unveil the timing and spatial extent of language processes in patients with epilepsy and may enhance knowledge of language lateralization and localization for use in preoperative planning.