title: Distributed source modeling of language with magnetoencephalography: application to patients with intractable epilepsy.
abstract: OBJECTIVE
  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 approximately 80 to 120 ms in response to novel words and sensory control stimuli (i.e., false fonts). Activity then spread to fusiform cortex approximately 160-200 ms, and was dominated by left hemisphere activity in response to novel words. From approximately 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.
  
  
  CONCLUSIONS
  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.
authors: Department of Psychiatry, University of California, San Diego, California, USA. camcdonald@ucsd.edu
authors: Carrie R
authors: CR
authors: McDonald
authors: Thomas
authors: T
authors: Thesen
authors: Donald J
authors: DJ
authors: Hagler
authors: Chad
authors: C
authors: Carlson
authors: Orrin
authors: O
authors: Devinksy
authors: Rubin
authors: R
authors: Kuzniecky
authors: William
authors: W
authors: Barr
authors: Lusineh
authors: L
authors: Gharapetian
authors: Amy
authors: A
authors: Trongnetrpunya
authors: Anders M
authors: AM
authors: Dale
authors: Eric
authors: E
authors: Halgren
mesh_terms: D000328:Adult; D000654:Amobarbital / Q000008:administration & dosage / Q000494:pharmacology; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000502:physiology / Q000503:physiopathology* / Q000601:surgery; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D005625:Frontal Lobe; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007600:Judgment / Q000187:drug effects / Q000502:physiology; D007802:Language; D007807:Language Tests; D015225:Magnetoencephalography / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000502:physiology / Q000503:physiopathology / Q000601:surgery; D011300:Preoperative Care; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D012660:Semantics; D013702:Temporal Lobe / Q000502:physiology / Q000503:physiopathology; D014705:Verbal Behavior / Q000187:drug effects / Q000502:physiology
chemical_list: D000654:Amobarbital