Hippocampus-Based Static Functional Connectivity Mapping within White Matter in Mild Cognitive Impairment

2021 ◽  
Author(s):  
Yuan Jiang ◽  
Pan Wang ◽  
Jiaping Wen ◽  
Jianlin Wang ◽  
Hongyi Li ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
White Matter ◽  
Functional Connectivity ◽  
Inferior Frontal Gyrus ◽  
Structural Connectivity ◽  
Memory Loss ◽  
Middle Temporal Gyrus ◽  
Pathophysiological Mechanism ◽  
Temporal Pole

Abstract Mild cognitive impairment (MCI), as the early important stage of Alzheimer’s disease (AD), is clinically characterized by memory loss and cognitive impairment closely associated with the hippocampus. Accumulating studies have confirmed the presence of neural signal changes within white matter (WM) in resting-state fMRI. However, how the abnormal hippocampus affects the WM regions remained unclear in MCI. The current study employed 43 MCI, 71 very MCI (VMCI) and 87 matched healthy controls (HC) participants from the public OASIS 3 dataset. Adopting left and right hippocampus (HIP.R) as seed points respectively, whole-brain functional connectivity (FC) maps were obtained for each subject. Subsequently, one-way ANOVA was performed to explore the abnormal FC regions with hippocampus within gray matter (GM)/WM. Further probabilistic tracking was performed to explore whether the abnormal FC corresponded to structural connectivity. Compared to HC, MCI and VMCI groups exhibited common reduced static FC (SFC) in the middle temporal gyrus within GM, and temporal pole and inferior frontal gyrus within WM. Specific dysconnectivity was shown in the cerebellum_crus2 and inferior temporal gyrus within GM, and frontal gyrus within WM. In addition, the fiber bundle connecting the HIP.R and temporal pole within WM showed abnormally increased mean diffusion in MCI. The current study extended a new functional imaging direction for exploring the mechanism of memory decline, and promoted the understanding for pathophysiological mechanism in different early stages of AD.

scholarly journals Distinctive Alterations of Functional Connectivity Strength between Vascular and Amnestic Mild Cognitive Impairment

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Hui Li ◽  
Shuai Gao ◽  
Xiuqin Jia ◽  
Tao Jiang ◽  
Kuncheng Li
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Functional Connectivity ◽  
Resting State ◽  
Inferior Frontal Gyrus ◽  
Brain Regions ◽  
Middle Temporal Gyrus ◽  
Resting State Functional Connectivity ◽  
Functional Connectivity Strength ◽  
Connectivity Strength

Widespread structural and functional alterations have been reported in the two highly prevalent mild cognitive impairment (MCI) subtypes, amnestic MCI (aMCI) and vascular MCI (VaMCI). However, the changing pattern in functional connectivity strength (FCS) remains largely unclear. The aim of the present study is to detect the differences of FCS and to further explore the detailed resting-state functional connectivity (FC) alterations among VaMCI subjects, aMCI subjects, and healthy controls (HC). Twenty-six aMCI subjects, 31 VaMCI participants, and 36 HC participants underwent cognitive assessments and resting-state functional MRI scans. At first, one-way ANCOVA and post hoc analysis indicated significant decreased FCS in the left middle temporal gyrus (MTG) in aMCI and VaMCI groups compared to HC, especially in the VaMCI group. Then, we selected the left MTG as a seed to further explore the detailed resting-state FC alterations among the three groups, and the results indicated that FC between the left MTG and some frontal brain regions were significantly decreased mainly in VaMCI. Finally, partial correlation analysis revealed that the FC values between the left MTG and left inferior frontal gyrus were positively correlated with the cognitive performance episodic memory and negatively related to the living status. The present study demonstrated that different FCS alterations existed in aMCI and VaMCI. These findings may provide a novel insight into the understanding of pathophysiological mechanisms underlying different MCI subtypes.

scholarly journals Increased hippocampal-inferior temporal cortex white matter connectivity following donepezil treatment in patients with mild cognitive impairment: A diffusion tensor probabilistic tractography study

2021 ◽  
Author(s):  
Gwang-Won Kim ◽  
Kwangsung Park ◽  
Gwang-Woo Jeong
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
White Matter ◽  
Diffusion Tensor ◽  
Early Stage ◽  
Structural Connectivity ◽  
Temporal Cortex ◽  
Mean Diffusivity ◽  
Inferior Temporal Cortex ◽  
Probabilistic Tractography

Abstract The incidence of Alzheimer’s disease (AD) has been increasing each year; however, few methods are available to identify the effects of treatment for AD. Defective hippocampus has been associated with mild cognitive impairment (MCI), an early stage of AD. However, the effect of donepezil treatment on hippocampus-related networks is unknown. The purpose of this study was to evaluate the hippocampal white matter (WM) connectivity following donepezil treatment in patients with MCI using probabilistic tractography, and to further determine the WM integrity and changes in brain volume. Magnetic resonance imaging and diffusion tensor imaging (DTI) data of patients with MCI before and after 6-month donepezil treatment were acquired. Volumes and DTI scalars of 11 regions of interest comprising the frontal and temporal cortices and subcortical regions were measured. Seed-based structural connectivity analyses were focused on the hippocampus. Compared with healthy controls, patients with MCI showed significantly decreased hippocampal volume and WM connectivity with the superior frontal gyrus, as well as increased mean diffusivity (MD) and radial diffusivity (RD) in the amygdala (p < 0.05, Bonferroni-corrected). After six months of donepezil treatment, patients with MCI showed increased hippocampal-inferior temporal gyrus (ITG) WM connectivity (p < 0.05, Bonferroni-corrected), which was normalized to the healthy control. These findings will be useful in developing theories to describe the etiology of MCI and the therapeutic role of anticholinesterases.

scholarly journals White Matter Abnormalities in Body Integrity Dysphoria

2021 ◽  
Author(s):  
Gianluca Saetta ◽  
Kathy Ruddy ◽  
Laura Zapparoli ◽  
Martina Gandola ◽  
Gerardo Salvato ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Inferior Frontal Gyrus ◽  
Structural Connectivity ◽  
The Body ◽  
Limb Amputation ◽  
Middle Temporal Gyrus ◽  
Imaging Data ◽  
Severe Condition ◽  
The Right

Body integrity dysphoria (BID) is a severe condition affecting non-psychotic individuals where a limb may be experienced as non-belonging, despite normal anatomical development and intact sensorimotor functions. Limb amputation is desired for restoring their own identity. We previously demonstrated altered brain structural (gray matter) and functional connectivity in 16 men with a long-lasting and exclusive desire for left leg amputation. Here we aimed to identify in the same sample altered patterns of white matter structural connectivity. Fractional anisotropy (FA), derived from Diffusion Tensor Imaging data, was considered as a measure of structural connectivity. Results showed reduced structural connectivity of: i) the right superior parietal lobule (rSPL) with the right cuneus, superior occipital and posterior cingulate gyri, and cuneus, ii) the pars orbitalis of the right middle frontal gyrus (rMFGOrb) with the putamen iii) the left middle temporal gyrus (lMTG) with the pars triangularis of the left inferior frontal gyrus. Increased connectivity was observed between the right paracentral lobule (rPLC) and the right caudate nucleus. By using a complementary method of investigation, we confirmed and extended previous results showing alterations in areas tuned to the processing of the sensorimotor representations of the affected leg (rPCL), and to higher-order components of bodily representation such as the body image (rSPL). Alongside this network for bodily awareness, other networks such as the limbic (rMFGOrb) and the mirror (lMTG) systems showed structural alterations as well. These findings consolidate current understanding of the neural correlates of BID, which might in turn guide diagnostics and rehabilitative treatments.

scholarly journals Differences Changes in Cerebellar Functional Connectivity Between Mild Cognitive Impairment and Alzheimer's Disease: A Seed-Based Approach

2021 ◽  
Vol 12 ◽  
Author(s):  
Fanyu Tang ◽  
Donglin Zhu ◽  
Wenying Ma ◽  
Qun Yao ◽  
Qian Li ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Functional Connectivity ◽  
Parietal Lobe ◽  
Inferior Frontal Gyrus ◽  
Superior Frontal Gyrus ◽  
Functional Connections ◽  
The Right

Background: Recent studies have discovered that functional connections are impaired among patients with Alzheimer's disease (AD), even at the preclinical stage. The cerebellum has been implicated as playing a role in cognitive processes. However, functional connectivity (FC) among cognitive sub-regions of the cerebellum in patients with AD and mild cognitive impairment (MCI) remains to be further elucidated.Objective: Our study aims to investigate the FC changes of the cerebellum among patients with AD and MCI, compared to healthy controls (HC). Additionally, we explored the role of cerebellum FC changes in the cognitive performance of all subjects.Materials: Resting-state functional magnetic resonance imaging (rs-fMRI) data from three different groups (28 AD patients, 26 MCI patients, and 30 HC) was collected. We defined cerebellar crus II and lobule IX as seed regions to assess the intragroup differences of cortico-cerebellar connectivity. Bias correlational analysis was performed to investigate the relationship between changes in FC and neuropsychological performance.Results: Compared to HC, AD patients had decreased FC within the caudate, limbic lobe, medial frontal gyrus (MFG), middle temporal gyrus, superior frontal gyrus, parietal lobe/precuneus, inferior temporal gyrus, and posterior cingulate gyrus. Interestingly, MCI patients demonstrated increased FC within inferior parietal lobe, and MFG, while they had decreased FC in the thalamus, inferior frontal gyrus, and superior frontal gyrus. Further analysis indicated that FC changes between the left crus II and the right thalamus, as well as between left lobule IX and the right parietal lobe, were both associated with cognitive decline in AD. Disrupted FC between left crus II and right thalamus, as well as between left lobule IX and right parietal lobe, was associated with attention deficit among subjects with MCI.Conclusion: These findings indicate that cortico-cerebellar FC in MCI and AD patients was significantly disrupted with different distributions, particularly in the default mode networks (DMN) and fronto-parietal networks (FPN) region. Increased activity within the fronto-parietal areas of MCI patients indicated a possible compensatory role for the cerebellum in cognitive impairment. Therefore, alterations in the cortico-cerebellar FC represent a novel approach for early diagnosis and a potential therapeutic target for early intervention.

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