title: Verbal memory and verbal fluency tasks used for language localization and lateralization during magnetoencephalography.
abstract: OBJECTIVE
  The aim of this study was to develop a presurgical magnetoencephalography (MEG) protocol to localize and lateralize expressive and receptive language function as well as verbal memory in patients with epilepsy. Two simple language tasks and a different analytical procedure were developed.
  
  
  METHODS
  Ten healthy participants and 13 epileptic patients completed two language tasks during MEG recording: a verbal memory task and a verbal fluency task. As a first step, principal component analyses (PCA) were performed on source data from the group of healthy participants to identify spatiotemporal factors that were relevant to these paradigms. Averaged source data were used to localize areas activated during each task and a laterality index (LI) was computed on an individual basis for both groups, healthy participants and patients, using sensor data.
  
  
  RESULTS
  PCA revealed activation in the left temporal lobe (300 ms) during the verbal memory task, and from the frontal lobe (210 ms) to the temporal lobe (500 ms) during the verbal fluency task in healthy participants. Averaged source data showed activity in the left hemisphere (250-750 ms), in Wernicke's area, for all participants. Left hemisphere dominance was demonstrated better using the verbal memory task than the verbal fluency task (F1,19=4.41, p=0.049). Cohen's kappa statistic revealed 93% agreement (k=0.67, p=0.002) between LIs obtained from MEG sensor data and fMRI, the IAT, electrical cortical stimulation or handedness with the verbal memory task for all participants. At 74%, agreement results for the verbal fluency task did not reach statistical significance.
  
  
  CONCLUSIONS
  Analysis procedures yielded interesting findings with both tasks and localized language-related activation. However, based on source localization and laterality indices, the verbal memory task yielded better results in the context of the presurgical evaluation of epileptic patients. The verbal fluency task did not add any further information to the verbal memory task as regards language localization and lateralization for most patients and healthy participants that would facilitate decision making prior to surgery.
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Maria Van der Knaap, Département de psychologie, Pavillon Marie-Victorin, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal, QC, Canada H3C 3J7; Centre de Recherche de l'Hôpital Sainte-Justine, Hôpital Sainte-Justine, CHU Sainte-Justine, 3175, Chemin de la Côte-Sainte-Catherine, Montréal, QC, Canada H3T 1C5. Electronic address: pirmoradi.mona@gmail.com.
authors.forename: Mona
authors.initials: M
authors.lastname: Pirmoradi
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Maria Van der Knaap, Département de psychologie, Pavillon Marie-Victorin, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal, QC, Canada H3C 3J7. Electronic address: boutheina.jemel@umontreal.ca.
authors.forename: Boutheina
authors.initials: B
authors.lastname: Jemel
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Maria Van der Knaap, Département de psychologie, Pavillon Marie-Victorin, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal, QC, Canada H3C 3J7; Centre de Recherche de l'Hôpital Sainte-Justine, Hôpital Sainte-Justine, CHU Sainte-Justine, 3175, Chemin de la Côte-Sainte-Catherine, Montréal, QC, Canada H3T 1C5. Electronic address: anne.gallagher@umontreal.ca.
authors.forename: Anne
authors.initials: A
authors.lastname: Gallagher
authors.affiliation: Centre de Recherche de l'Hôpital Sainte-Justine, Hôpital Sainte-Justine, CHU Sainte-Justine, 3175, Chemin de la Côte-Sainte-Catherine, Montréal, QC, Canada H3T 1C5. Electronic address: julie.tremblay3@gmail.com.
authors.forename: Julie
authors.initials: J
authors.lastname: Tremblay
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Maria Van der Knaap, Département de psychologie, Pavillon Marie-Victorin, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal, QC, Canada H3C 3J7; Centre de Recherche de l'Hôpital Sainte-Justine, Hôpital Sainte-Justine, CHU Sainte-Justine, 3175, Chemin de la Côte-Sainte-Catherine, Montréal, QC, Canada H3T 1C5. Electronic address: fabien.dhondt@gmail.com.
authors.forename: Fabien
authors.initials: F
authors.lastname: D'Hondt
authors.affiliation: Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame, 1560, rue Sherbrooke Est, Montréal, QC, Canada H2L 4M1. Electronic address: d.nguyen@umontreal.ca.
authors.forename: Dang Khoa
authors.initials: DK
authors.lastname: Nguyen
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Maria Van der Knaap, Département de psychologie, Pavillon Marie-Victorin, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal, QC, Canada H3C 3J7. Electronic address: renee.beland@gmail.com.
authors.forename: Renée
authors.initials: R
authors.lastname: Béland
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Maria Van der Knaap, Département de psychologie, Pavillon Marie-Victorin, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal, QC, Canada H3C 3J7; Centre de Recherche de l'Hôpital Sainte-Justine, Hôpital Sainte-Justine, CHU Sainte-Justine, 3175, Chemin de la Côte-Sainte-Catherine, Montréal, QC, Canada H3T 1C5. Electronic address: maryse.lassonde@umontreal.ca.
authors.forename: Maryse
authors.initials: M
authors.lastname: Lassonde
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology* / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007802:Language; D007807:Language Tests; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D025341:Principal Component Analysis; D013067:Speech Perception / Q000502:physiology; D014705:Verbal Behavior / Q000502:physiology*; D055815:Young Adult
keywords: Language; Magnetoencephalography; Presurgical evaluation; Verbal fluency; Verbal memory