Enhanced Gamma Activity and Cross-Frequency Interaction of Resting-State Electroencephalographic Oscillations in Patients with Alzheimer's Disease.

Author: Wang J1,2,3, Fang Y4, Wang X1,2,3, Yang H4,5, Yu X1,2,3, Wang H1,2,3
1Peking University Sixth Hospital (Institute of Mental Health)Beijing, China.
2National Clinical Research Center for Mental Disorders, Key Laboratory of Mental Health, Ministry of Health, Peking UniversityBeijing, China.
3Beijing Municipal Key Laboratory for Translational Research on Diagnosis and Treatment of DementiaBeijing, China.
4National Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal UniversityBeijing, China.
5IDG/McGovern Institute for Brain Research, Beijing Normal UniversityBeijing, China.
Conference/Journal: Front Aging Neurosci.
Date published: 2017 Jul 26
Other: Volume ID: 9 , Pages: 243 , Special Notes: doi: 10.3389/fnagi.2017.00243. eCollection 2017. , Word Count: 240

Cognitive impairment, functional decline and behavioral symptoms that characterize Alzheimer's disease (AD) are associated with perturbations of the neuronal network. The typical electroencephalographic (EEG) features in AD patients are increased delta or theta rhythm and decreased alpha or beta rhythm activities. However, considering the role of cross-frequency couplings in cognition, the alternation of cross-frequency couplings in AD patients is still obscure. This study aims to explore the interaction dynamics between different EEG oscillations in AD patients. We recorded the resting eye-closed EEG signals in 8 AD patients and 12 healthy volunteers. By analyzing the wavelet power spectrum and bicoherence of EEG, we found enhanced gamma rhythm power in AD patients in addition to the increased delta and decreased alpha power. Furthermore, an enhancement of the cross-frequency coupling strength between the beta/gamma and low-frequency bands was observed in AD patients compared to healthy controls (HCs). We propose that the pathological increase of ongoing gamma-band power might result from the disruption of the GABAergic interneuron network in AD patients. Furthermore, the cross-frequency overcouplings, which reflect the enhanced synchronization, might indicate the attenuated complexity of the neuronal network, and AD patients have to use more neural resources to maintain the resting brain state. Overall, our findings provide new evidence of the disturbance of the brain oscillation network in AD and further deepen our understanding of the central mechanisms of AD.

KEYWORDS: Alzheimer’s disease; EEG; cross-frequency coupling; oscillations; resting-state

PMID: 28798683 PMCID: PMC5526997 DOI: 10.3389/fnagi.2017.00243