| Objective:This study is based on resting state MRI and uses multi-modaldata analysis methods of Re Ho,DC,VMHC,and intra-ICA network connectivity to explore DMN functional activity and connectivity changes in individuals with MCI at rest,with the goal of improving understanding of the pathogenesis and pathophysiology of patients with MCI and also providing more imaging references for physicians’ diagnoses.Methods:24 MCI patients were selected according to inclusion criteria,22 in the healthy control(HC)group,and the two groups were nearly matched in age,sex,and education.All MCI and HC subjects were first tested for cognitive performance using the Simple Mental Status Assessment Scale(MMSE)and the Montreal Cognitive Assessment Scale(Mo CA).All subjects were then subjected to static functional magnetic resonance(f MRI)scans and the data were pre-processed to analyze functional activity and connectivity changes in DMN in the MCI and HC groups using Re Ho,DC,VMHC and ICA networks,respectively,and correlated to cognitive scales.Intergroup comparison was performed using a doublesample T-assay statistical method and results were presented using Xjview and MRICROGL software.Results:1.General clinical information: There were no statistically significant differences in sex,age,and education level in the MCI group compared to the HC group;in MMSE scores and Mo CA scores,the MCI group had significantly lower scale scores compared with the HC group,and the differences were statistically significant.2.Comparison of Re Ho values of DMN in two groups: the MCI group had reduced Re Ho values in the left anterior cingulate and paracingulate gyrus,left medial superior frontal gyrus,and left angular gyrus,while Re Ho values increased in the left precuneus.the Re Ho values of the left anterior cingulate and paracingulate gyrus and left medial superior frontal gyrus in the MCI group were positively correlated with Mo Ca scores.3.Comparison of DC values of DMN in two groups: In the MCI group,in comparison to the HC group,DC values in left middle temporal gyrus,in the MCI group,the right middle temporal gyrus and right postcentral gyrus were decreased in size,whereas right hippocampal and right superior occipital gyrus DC values were increased.4.Comparison of VMHC values of DMN in two groups: The MCI group had reduced VMHC in the bilateral medial superior frontal gyrus,bilateral posterior cingulate gyrus and no brain regions with increased VMHC compared to HC.5.Functional connectivity within the DMN network in the two groups: in the MCI group compared to the HC group,the MCI group had decreased functional connectivity in left middle temporal gyrus,whereas functional connectivity was increased in the left hippocampus,bilateral cuneus and left precuneus.Conclusions:1.It is possible that the presence of synchronous changes in functional activity in the local brain regions of the default mode network of MCI patients is related to the neuropathological mechanism of their cognitive impairment.2.Abnormalities in functional connectivity exist in the default mode network of patients with MCI.Through the use of degree centrality,mirror isochronous connectivity,and within-network methods of functional connectivity analysis,functional connectivity strength,left and right hemisphere synergistic functional connectivity,and within-network connectivity of the default mode network were found to be altered,suggesting that cognitive dysfunction in MCI patients may be linked to these changes in functional connectivity.3.Multi-dimensional and multi-parametric analysis of functional MRI data helps to capture the global analysis of neural mechanisms in patients with MCI,and should be a sensitive and efficient means of detecting brain network changes in patients with MCI. |
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