title: Altered generation of spontaneous oscillations in Alzheimer's disease.
abstract: Slowing of spontaneous alpha oscillations and an anterior shift of a source of alpha activity (8-13 Hz) have been consistently reported in the EEG studies of Alzheimer's disease (AD). It is unknown whether these changes are associated with a gradual shift in location and frequency of existing sources or rather with the involvement of a new set of oscillators. We addressed this question by applying source modeling (minimum current estimates, MCE) to spontaneous alpha activity recorded with a 306-channel MEG system from eleven non-medicated AD patients with mild to moderate cognitive impairment and twelve age-matched controls during the eyes-closed session. AD patients had predominant lower alpha band sources in the temporal regions, whereas in the controls, robust alpha sources were found near the parieto-occipital sulcus. Activation within the parieto-occipital region was significantly weaker, and activation in the right temporal area was significantly enhanced in the AD patients. These results suggest an increased temporal-lobe contribution coinciding with parieto-occipital deficits. We propose that MCE, which provides simultaneous mapping of several oscillatory sources, might be useful for detecting neurophysiological abnormalities associated with AD in combination with other neuropsychological and neurological measures.
authors.affiliation: Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, Finland. darja.osipova@cbru.helsinki.fi
authors.forename: Daria
authors.initials: D
authors.lastname: Osipova
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ahveninen
authors.forename: Ole
authors.initials: O
authors.lastname: Jensen
authors.forename: Ari
authors.initials: A
authors.lastname: Ylikoski
authors.forename: Eero
authors.initials: E
authors.lastname: Pekkonen
mesh_terms: D000368:Aged; D000513:Alpha Rhythm; D000544:Alzheimer Disease / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008959:Models, Neurological; D009778:Occipital Lobe / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology