Objective: We examined the hypothesis that cognitive dy-sfunction in Alzheimer’s disease is associated with abnormal spontaneous fluc tuations of EEG synchronization levels during an eyes-closed resting state. Met ho...Objective: We examined the hypothesis that cognitive dy-sfunction in Alzheimer’s disease is associated with abnormal spontaneous fluc tuations of EEG synchronization levels during an eyes-closed resting state. Met hods: EEGs were recorded during an eyes-closed resting state in Alzheimer patie nts (N=24;9 males; mean age 76.3 years; SD 7.8; range 59-86) and nondemented su bjects with subjective memory complaints (N=19;9males;mean age 76.1 years; SD 6. 7; range: 67-89). The mean level of synchronization was determined in different frequency bands with the synchronization likelihood and fluctuations of the syn chronization level were analysed with detrended fluctuation analysis (DFA). Resu lts: The mean level of EEG synchronization was lower in Alzheimer patients in th e upper alpha (10-13 Hz) and beta (13-30 Hz) band. Spontaneous fluctuations of synchronization were diminished in Alzheimer patients in the lower alpha (8-10 Hz) and beta bands. In patients as well as controls the synchronization fluctuat ions showed a scale-free pattern. Conclusions: Alzheimer’s disease is characte rized both by a lower mean level of functional connectivity as well as by dimini shed fluctuations in the level of synchronization.The dynamics of these fluctuat ions in patients and controls was scale-free which might point to self-organiz ed criticality of neural networks in the brain. Significance: Impaired functiona l connectivity can manifest itself not only in decreased levels of synchronizati on but also in disturbed fluctuations of synchronization levels.展开更多
文摘Objective: We examined the hypothesis that cognitive dy-sfunction in Alzheimer’s disease is associated with abnormal spontaneous fluc tuations of EEG synchronization levels during an eyes-closed resting state. Met hods: EEGs were recorded during an eyes-closed resting state in Alzheimer patie nts (N=24;9 males; mean age 76.3 years; SD 7.8; range 59-86) and nondemented su bjects with subjective memory complaints (N=19;9males;mean age 76.1 years; SD 6. 7; range: 67-89). The mean level of synchronization was determined in different frequency bands with the synchronization likelihood and fluctuations of the syn chronization level were analysed with detrended fluctuation analysis (DFA). Resu lts: The mean level of EEG synchronization was lower in Alzheimer patients in th e upper alpha (10-13 Hz) and beta (13-30 Hz) band. Spontaneous fluctuations of synchronization were diminished in Alzheimer patients in the lower alpha (8-10 Hz) and beta bands. In patients as well as controls the synchronization fluctuat ions showed a scale-free pattern. Conclusions: Alzheimer’s disease is characte rized both by a lower mean level of functional connectivity as well as by dimini shed fluctuations in the level of synchronization.The dynamics of these fluctuat ions in patients and controls was scale-free which might point to self-organiz ed criticality of neural networks in the brain. Significance: Impaired functiona l connectivity can manifest itself not only in decreased levels of synchronizati on but also in disturbed fluctuations of synchronization levels.
