Focal temporoparietal slow activity in Alzheimer’s disease revealed by magnetoencephalography

Fernández, Alberto; Maestú, Fernando; Amo, Carlos; Gil, Pedro; Fehr, Thorsten; Wienbruch, Christian; Rockstroh, Brigitte; Elbert, Thomas; Ortiz, Tomás

doi:10.1016/s0006-3223(02)01366-5

Cited by 131 publications

(99 citation statements)

References 39 publications

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“…Their findings suggested that MEG slowing in AD might not be due to the slowing of existing sources, but it might be owing to an increase in activation of low frequency generators. This hypothesis is supported by the findings of Fernández et al [46,47], which observed an enhanced value in dipole density at δ and θ bands, when they analysed spontaneous MEG oscillations in AD.…”

Section: Discussionsupporting

confidence: 76%

Evaluation of spectral ratio measures from spontaneous MEG recordings in patients with Alzheimer's disease

Poza

Hornero

Abásolo

et al. 2008

Computer Methods and Programs in Biomedicine

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Section: Discussionsupporting

confidence: 76%

Evaluation of spectral ratio measures from spontaneous MEG recordings in patients with Alzheimer's disease

Poza

Hornero

Abásolo

et al. 2008

Computer Methods and Programs in Biomedicine

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“…S1 A and B)]. This is in agreement with the well-known slowing of the alpha rhythm in AD (17)(18)(19). Thus, to avoid confounding frequency and amplitude effects, we defined the alphafrequency band to be 6-13 Hz.…”

Section: Resultssupporting

confidence: 61%

“…2 A and B). The following filter settings were used (cut-off frequencies, filter order): delta (2-3 Hz, 251), theta (4 -5 Hz, 63), alpha (6 -13 Hz, 28), beta (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)28), and gamma (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)13). The mean oscillation amplitude was computed as the time-averaged amplitude envelope.…”

Section: Methodsmentioning

confidence: 99%

Altered temporal correlations in parietal alpha and prefrontal theta oscillations in early-stage Alzheimer disease

Montez

Poil

Jones

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

278

230

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Encoding and retention of information in memory are associated with a sustained increase in the amplitude of neuronal oscillations for up to several seconds. We reasoned that coordination of oscillatory activity over time might be important for memory and, therefore, that the amplitude modulation of oscillations may be abnormal in Alzheimer disease (AD). To test this hypothesis, we measured magnetoencephalography (MEG) during eyes-closed rest in 19 patients diagnosed with early-stage AD and 16 agematched control subjects and characterized the autocorrelation structure of ongoing oscillations using detrended fluctuation analysis and an analysis of the life-and waiting-time statistics of oscillation bursts. We found that Alzheimer's patients had a strongly reduced incidence of alpha-band oscillation bursts with long life-or waiting-times (< 1 s) over temporo-parietal regions and markedly weaker autocorrelations on long time scales (1-25 seconds). Interestingly, the life-and waiting-times of theta oscillations over medial prefrontal regions were greatly increased. Whereas both temporo-parietal alpha and medial prefrontal theta oscillations are associated with retrieval and retention of information, metabolic and structural deficits in early-stage AD are observed primarily in temporo-parietal areas, suggesting that the enhanced oscillations in medial prefrontal cortex reflect a compensatory mechanism. Together, our results suggest that amplitude modulation of neuronal oscillations is important for cognition and that indices of amplitude dynamics of oscillations may prove useful as neuroimaging biomarkers of early-stage AD.Alzheimer's disease ͉ magnetoencephalography ͉ neuronal oscillations ͉ resting-state brain activity ͉ temporal correlations P sychological and neuroimaging data suggest that the brain performs many important functions during rest, such as retrieval and manipulation of information in short-term memory, and problem-solving and planning (1, 2). These resting-state functions may represent an essential aspect of human selfawareness and are susceptible to impairment in brain-related disorders including depression, schizophrenia, and dementia (3).Neuroimaging has identified anatomical patterns of activity that are remarkably consistent across resting-state experiments, most notably in the precuneus, lateral parietal and medial prefrontal cortices (4, 5). The existence of such a ''resting-state network'' has been suggested to reflect a ''default mode'' of brain operation in the absence of goal-directed behavior (6). Coordination of anatomically distributed activity during rest has been studied extensively by computing correlations between neuronal signals from different brain areas (Fig. 1). This approach has revealed aberrant resting-state networks in Alzheimer disease (AD) (7-9) and other disorders (4, 10, 11).For cognitive processing, coordination of local brain activity over time may be just as important as the coordination of simultaneous activity in anatomically distinct brain regions and may be refl...

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“…Mean neural complexity is higher in AD group than in control subjects group for the low frequency bands (2-4 Hz, 4-8 Hz and 8-12 Hz) and lower in the others (from 14 to 40 Hz). Other authors have studied spectral analysis in AD patients' EEGs [7] and MEGs [8,9]. They found an increased EEG/MEG activity in AD patients compared with control subjects in delta and theta bands.…”

Section: Discussionmentioning

confidence: 99%

“…Spectral analysis seems to discriminate AD patients from control subjects through an increased EEG/MEG activity in delta and theta bands associated with AD [7][8][9]. On the other hand, some authors have studied this dementia using non-linear analysis.…”

Section: Introductionmentioning

confidence: 99%

Complexity analysis of the magnetoencephalogram background activity in Alzheimer's disease patients

Gómez

Hornero

Abásolo

et al. 2006

Medical Engineering & Physics

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Focal temporoparietal slow activity in Alzheimer’s disease revealed by magnetoencephalography

Cited by 131 publications

References 39 publications

Evaluation of spectral ratio measures from spontaneous MEG recordings in patients with Alzheimer's disease

Evaluation of spectral ratio measures from spontaneous MEG recordings in patients with Alzheimer's disease

Altered temporal correlations in parietal alpha and prefrontal theta oscillations in early-stage Alzheimer disease

Complexity analysis of the magnetoencephalogram background activity in Alzheimer's disease patients

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