title: Event-related synchronization of alpha activity in early Alzheimer's disease and mild cognitive impairment: an MEG study combining beamformer and group comparison.
abstract: In patients with Alzheimer's disease (AD), it is sometimes challenging to identify typical findings in electroencephalography (EEG) or magnetoencephalography (MEG) such as a slowing of the posterior dominant activity or an increase in slow activity. In this MEG study, we evaluated the event-related synchronization (ERS) of alpha activity after eye closing in patients with early AD and mild cognitive impairment (MCI) who presented no slow MEG pattern. Thirteen patients with probable AD and thirteen patients with MCI, who met NINCDS-ADRDA and Petersen's diagnostic criteria, respectively, were enrolled. We also selected fourteen age-matched normal control subjects. MEG activity was acquired during eye-open and eye-closed states. The ERS after eye closing within 8-15Hz frequency band was calculated and its cortical source was superimposed on the individual's MRI by using the beamformer implemented in Brain Electrical Source Analysis (BESA). The Source image was converted into a standardized image, and group comparisons across patients with AD, MCI and controls were performed using BrainVoyager QX. The averaged ERS was observed dominantly in posterior regions in all three groups. Significant difference in ERS was observed only for the comparison between AD patients and controls, with AD patients showing increased ERS in frontal regions. Frontal shift of posterior alpha activity was observed clearly in AD patients using the combination of beamformer and group comparison.
authors.affiliation: Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan. kurimmoto@psy.med.osaka-u.ac.jp
authors.forename: Ryu
authors.initials: R
authors.lastname: Kurimoto
authors.forename: Ryouhei
authors.initials: R
authors.lastname: Ishii
authors.forename: Leonides
authors.initials: L
authors.lastname: Canuet
authors.forename: Koji
authors.initials: K
authors.lastname: Ikezawa
authors.forename: Michiyo
authors.initials: M
authors.lastname: Azechi
authors.forename: Masao
authors.initials: M
authors.lastname: Iwase
authors.forename: Tetsuhiko
authors.initials: T
authors.lastname: Yoshida
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Kazui
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yoshimine
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Takeda
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000503:physiopathology; D003072:Cognition Disorders / Q000175:diagnosis* / Q000503:physiopathology; D003344:Cortical Synchronization; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male