title: Brain connectivity of patients with Alzheimer's disease by coherence and cross mutual information of electroencephalograms during photic stimulation.
abstract: Alzheimer's disease (AD) is a neurodegenerative disease, usually diagnosed by neuropsychological tests, and excluded from other cerebral diseases by brain images. An electroencephalogram (EEG) provides a means of disclosing the reduced functional couplings between brain regions that occurs with AD. In the present study, 16 probable AD patients and 15 age-matched, gender-matched normal subjects were enrolled. Spectral coherence and cross mutual information (CMI) were used to analyze EEGs during intermittent photic stimulation (PS). Ocular- and heartbeat-related source components (SCs) obtained from multi-channel EEGs by the independent component analysis were discarded, and the photic-related SCs were reduced using a comb filter. The undisturbed SCs and photic-related SCs before and after photic reduction were used to reconstruct photic-preserved EEGs and photic-reduced EEGs, from which harmonic coherences (direct photic-driving response) and rhythmic coherences and CMI (indirect photic affection) were computed, respectively. Our results indicate that the rhythmic coherences (particularly in the alpha and beta bands) and CMI variables as well as the harmonic coherences (particularly related to 3-Hz PS) were significantly lower in the probable AD than in normal subjects, whereas the variables derived from the resting EEGs were not statistically significant. This finding implied that the variables obtained during PS could be used to disclose impaired intra-brain associations in probable AD.
authors: Department of Electrical Engineering, Chang Gung University, Taoyuan 333, Taiwan, ROC. chanhl@mail.cgu.edu.tw
authors: Hsiao-Lung
authors: HL
authors: Chan
authors: Ju-His
authors: JH
authors: Chu
authors: Hon-Chung
authors: HC
authors: Fung
authors: Yu-Tai
authors: YT
authors: Tsai
authors: Ling-Fu
authors: LF
authors: Meng
authors: Chin-Chang
authors: CC
authors: Huang
authors: Wen-Chun
authors: WC
authors: Hsu
authors: Pei-Kuang
authors: PK
authors: Chao
authors: Jiun-Jie
authors: JJ
authors: Wang
authors: Jiann-Der
authors: JD
authors: Lee
authors: Yau-Yau
authors: YY
authors: Wai
authors: Meng-Tsan
authors: MT
authors: Tsai
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology* / Q000503:physiopathology*; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology; D010775:Photic Stimulation; D013223:Statistics as Topic / Q000379:methods*