Source estimation of spontaneous MEG oscillations in mild cognitive impairment.

Mild cognitive impairment (MCI) is a memory disorder often preceding Alzheimer's disease (AD). AD has been shown to be associated with abnormal generation of spontaneous electromagnetic activity. We investigated whether the cortical generation of spontaneous brain oscillations in MCI shows changes resembling those observed in AD. A minimum current estimates algorithm was applied to identify cortical sources of magnetoencephalographic (MEG) spontaneous brain oscillations in male MCI patients with a clear memory disorder and in healthy elderly controls. This data was subsequently compared to a male subsample of AD patients from an earlier study. While there were clear oscillatory abnormalities in AD patients, there was no evidence of significant changes in the alpha source distribution in MCI patients as compared to healthy controls. Deficits in the distribution of oscillatory sources in the resting state are thus likely to occur at later stages of cognitive impairment than MCI.