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Front Hum Neurosci. 2018 Oct 29;12:413. doi: 10.3389/fnhum.2018.00413. eCollection 2018.

Disrupted Functional Connectivity of Cornu Ammonis Subregions in Amnestic Mild Cognitive Impairment: A Longitudinal Resting-State fMRI Study.

Li H1,2, Jia X3,4, Qi Z1,2, Fan X1, Ma T1, Pang R1, Ni H1, Li CR5,6,7, Lu J1,2, Li K1,2.

Author information

1
Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China.
2
Beijing Key Laboratory of MRI and Brain Informatics, Beijing, China.
3
Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
4
Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
5
Department of Psychiatry, Yale School of Medicine, Yale University, New Haven, CT, United States.
6
Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, United States.
7
Beijing Huilongguan Hospital, Beijing, China.

Abstract

Background: The cornu ammonis (CA), as part of the hippocampal formation, represents a primary target region of neural degeneration in amnestic mild cognitive impairment (aMCI). Previous studies have revealed subtle structural deficits of the CA subregions (CA1-CA3, bilateral) in aMCI; however, it is not clear how the network function is impacted by aMCI. The present study examined longitudinal changes in resting state functional connectivity (FC) of each CA subregion and how these changes relate to neuropsychological profiles in aMCI. Methods: Twenty aMCI and 20 healthy control (HC) participants underwent longitudinal cognitive assessment and resting state functional MRI scans at baseline and 15 months afterward. Imaging data were processed with published routines in SPM8 and CONN software. Two-way analysis of covariance was performed with covariates of age, gender, education level, follow up interval, gray matter volume, mean FD, as well as global correlation (GCOR). Pearson's correlation was conducted to evaluate the relationship between the longitudinal changes in CA subregional FC and neuropsychological performance in aMCI subjects. Results: Resting state FC between the right CA1 and right middle temporal gyrus (MTG) as well as between the left CA2 and bilateral cuneal cortex (CC) were decreased in aMCI subjects as compared to HC. Longitudinal decrease in FC between the right CA1 and right MTG was correlated with reduced capacity of episodic memory in aMCI subjects. Conclusion: The current findings suggest functional alterations in the CA subregions. CA1 connectivity with the middle temporal cortex may represent an important neural marker of memory dysfunction in aMCI.

KEYWORDS:

amnestic mild cognitive impairment; cornu ammonis; functional connectivity; hippocampus; longitudinal study

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