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Received: 2005-12-28

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Journal of Zhejiang University SCIENCE B 2006 Vol.7 No.5 P.357-364


Inter- and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task

Author(s):  Jiang Zheng-yan, Zheng Lei-lei

Affiliation(s):  Department of Psychiatry, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China

Corresponding email(s):   Jiang_zju@mail.hz.zj.cn

Key Words:  Mild cognitive impairment (MCI), EEG, Coherence, Working memory, Cortical connectivity

Jiang Zheng-yan, Zheng Lei-lei. Inter- and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task[J]. Journal of Zhejiang University Science B, 2006, 7(5): 357-364.

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author="Jiang Zheng-yan, Zheng Lei-lei",
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%0 Journal Article
%T Inter- and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task
%A Jiang Zheng-yan
%A Zheng Lei-lei
%J Journal of Zhejiang University SCIENCE B
%V 7
%N 5
%P 357-364
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%D 2006
%I Zhejiang University Press & Springer
%DOI 10.1631/jzus.2006.B0357

T1 - Inter- and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task
A1 - Jiang Zheng-yan
A1 - Zheng Lei-lei
J0 - Journal of Zhejiang University Science B
VL - 7
IS - 5
SP - 357
EP - 364
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Y1 - 2006
PB - Zhejiang University Press & Springer
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DOI - 10.1631/jzus.2006.B0357

Objective: To assess functional relationship by calculating inter- and intra-hemispheric electroencephalography (EEG) coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Methods: The sample consisted of 69 subjects: 35 patients (n=17 males, n=18 females; 52~71 years old) and 34 normal controls (n=17 males, n=17 females; 51~63 years old). Mini-mental state examination (MMSE) of two groups revealed that the scores of MCI patients did not differ significantly from those of normal controls (P>0.05). In EEG recording, subjects were performed at rest and during working memory task. EEG signals from F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 electrode pairs are resulted from the inter-hemispheric action, and EEG signals from F3-C3, F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs are resulted from the intra-hemispheric action for delta (1.0~3.5 Hz), theta (4.0~7.5 Hz), alpha-1 (8.0~10.0 Hz), alpha-2 (10.5~13.0 Hz), beta-1 (13.5~18.0 Hz) and beta-2 (18.5~30.0 Hz) frequency bands. The influence of inter- and intra-hemispheric coherence on EEG activity with eyes closed was examined using fast Fourier transformation from the 16 sampled channels. Results: During working memory tasks, the inter- and intra-hemispheric EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P<0.05). However, there was no significant difference in inter- and intra-hemispheric EEG coherences between two groups at rest. Conclusion: Experimental results comprise evidence that MCI patients have higher degree of functional connectivity between hemispheres and in hemispheres during working condition. It suggests that MCI may be associated with compensatory processes during working memory tasks between hemispheres and in hemispheres. Moreover, failure of normal cortical connections may exist in MCI patients.

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