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Study of fMRI of brain networks of patients with Parkinson's disease accompanied by cognition impairment
PENGQiaojun, WANGYufeng, TANJuan, HOUChangyue, WANGYinxu, WANGXiaoming
Chinese Journal of Alzheimer's Disease and Related Disorders ›› 2020, Vol. 3 ›› Issue (4) : 267-273.
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Abbreviation (ISO4): Chinese Journal of Alzheimer's Disease and Related Disorders
Editor in chief: Jun WANG
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Study of fMRI of brain networks of patients with Parkinson's disease accompanied by cognition impairment
Objective: Investigate the changes of brain networks in patients with Parkinson's disease accompanied by cognitive impairment(PD-CI) in order to provide valuable information for the study of its neuroimaging mechanisms. Methods: A total of 22 patients with primary PD who visited neurology clinic of the Affiliated Hospital of North Sichuan Medical College from May 2019 to May 2020 were included. MoCA and MMSE were used to evaluate all subjects, divided them into 12 Parkinson's Disease with Cognitive Impairment (PD-CI), 10 Parkinson's disease with normal cognitive function(PD-NC), and 25 healthy controls (HC) matched with their age, sex, and years of education. Standard clinical feature assessment and Rs-fMRI scan were performed for all subjects. SPASS21.0 software was used to perform statistical analysis on the experimental data, and statistical methods such as independent sample t-test, one-way analysis of variance and chi-square test statistical methods were used. Regional homogeneity was adopted to analyze the Rs-fMRI data of patients in the three groups respectively, and brain regions with differences in ReHo values between each group were selected as region of interest (ROI), and then whole-brain FC analysis was conducted by using ROI-based functional connectivity (FC) method. Results: (1) ReHo value result analysis: compared with the HC group, the ReHo values of left cerebellar Angle 1, right orbital superior frontal gyrus, left medial superior frontal gyrus, right dorsolateral superior frontal gyrus, left inferior marginal angular gyrus, left medial and side cingulate gyrus were decreased in the PD-CI group, while those of right tongue gyrus were increased. Compared with the HC group, the values of ReHo in the left cerebellar Angle 1, right orbital superior frontal gyrus, left medial superior frontal gyrus, and left acromial inferior margin angular gyrus were decreased in the PD-NC group, and no regions with higher ReHo values were found. Compared with the PD-NC group, the right dorsolateral superior frontal gyrus had lower ReHo value and the right lingual gyrus had higher ReHo value in the PD-CI group. (2) FC result analysis: Compared with the HC group, in the PD-CI group, the functional connections between left medial superior frontal gyrus and left parahippocampal gyrus were weakened, the functional connections between left inferior marginal gyrus, left central sulcus lid and left triangular inferior frontal gyrus were weakened too, while that between right dorsolateral superior frontal gyrus and right precuneus and between left inferior marginal gyrus and right superior pillow gyrus were strengthened. Compared with the HC group, in the PD-NC group, the functional connection between left medial superior frontal gyrus and left parahippocampal gyrus and between left inferior marginal Angle gyrus and left triangular inferior frontal gyrus were weakened, while that between right dorsolateral superior frontal gyrus and right precuneus was strengthened. Compared with the PD-NC group, in the PD-CI group, the functional connections between the left inferior parietal gyrus and the left middle temporal gyrus and the left posterior central gyrus were weakened. Conclusion: (1) The decreasing of ReHo values of left cerebellar Angle 1, right orbitofrontal superior gyrus, left medial superior gyrus, right dorsolateral superior gyrus, left inferior marginal gyrus, left medial and paracingulate gyrus of PD-CI patients were associated with cognitive impairment of PD patients, while the increasing of ReHo values of right tongue gyrus may be the compensatory performance of cognitive function. (2) The default mode network (DMN) functional connections of PD-CI patients was changed and the change of DMN functional connections may be the key to their cognitive decline.These conclusions may help to further study the potential mechanism of PD-related cognitive impairment, and provide new ideas for the treatment of PD patients and their cognitive dysfunction.
Parkinson's disease / Cognition impairment / Resting-state functional magnetic resonance imaging / Brain network
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Cognitive decline is a major disabling feature in Parkinson's disease (PD). Multimodal imaging studies have shown functional disruption in neurocognitive networks related to cognitive impairment. However, it remains unknown whether these changes are related to gray matter loss, or whether they outline network vulnerability in the early stages of cognitive impairment. In this work, we intended to assess functional connectivity and graph theoretical measures and their relation to gray matter loss in Parkinson's disease with mild cognitive impairment (PD-MCI). We recruited 53 Parkinson's disease patients and classified them for cognitive impairment using Level-1 Movement Disorders Society-Task Force Criteria. Voxel-based morphometry, functional connectivity and graph theoretical measures were obtained on a 3-Tesla MRI scanner. Loss of gray matter was observed in the default mode network (bilateral precuneus), without a corresponding disruption of functional or graph theoretical properties. However, functional and graph theoretical changes appeared in salience network nodes, without evidence of gray matter loss. Global cognition and executive scores showed a correlation with node degree in the right anterior insula. We also found a correlation between visuospatial scores and right supramarginal gyrus node degree. Our findings highlight the loss of functional connectivity and topological features without structural damage in salience network regions in PD-MCI. They also underline the importance of multimodal hubs in the transition to mild cognitive impairment. This functional disruption in the absence of gray matter atrophy suggests that the salience network is a key vulnerable system at the onset of mild cognitive impairment in PD.© 2019 Wiley Periodicals, Inc.
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Executive function is a product of the coordinated operation of multiple neural systems and an essential prerequisite for a variety of cognitive functions. The prefrontal cortex is known to be a key structure for the performance of executive functions. To accomplish the coordinated operations of multiple neural systems, the prefrontal cortex must monitor the activities in other cortical and subcortical structures and control and supervise their operations by sending command signals, which is called top-down signaling. Although neurophysiological and neuroimaging studies have provided evidence that the prefrontal cortex sends top-down signals to the posterior cortices to control information processing, the neural correlate of these top-down signals is not yet known. Through use of the paired association task, it has been demonstrated that top-down signals are used to retrieve specific information stored in long-term memory. Therefore, we used a paired association task to examine the neural correlates of top-down signals in the prefrontal cortex. The preliminary results indicate that 32% of visual neurons exhibit pair-selectivity, which is similar to the characteristics of pair-coding activities in temporal neurons. The latency of visual responses in prefrontal neurons was longer than bottom-up signals but faster than top-down signals in inferior temporal neurons. These results suggest that pair-selective visual responses may be top-down signals that the prefrontal cortex provides to the temporal cortex, although further studies are needed to elucidate the neural correlates of top-down signals and their characteristics to understand the neural mechanism of executive control by the prefrontal cortex. Copyright © 2013. Published by Elsevier Ltd.
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Cognitive impairment in patients with Parkinson's disease is gaining increased clinical significance owing to the relative success of therapeutic approaches to the motor symptoms of this disorder. Early investigations contributed to the concept of subcortical dementia associated with bradyphrenia and cognitive rigidity. For cognition in parkinsonian disorders, this notion developed into the concept of mild cognitive impairment and fronto-executive dysfunction in particular, driven mainly by dopaminergic dysmodulation and manifesting as deficits in flexibility, planning, working memory, and reinforcement learning. However, patients with Parkinson's disease could also develop a syndrome of dementia that might depend on non-dopaminergic, cholinergic cortical dysfunction. Recent findings, supplemented by advances in neuroimaging and genetic research, reveal substantial heterogeneity in the range of cognitive deficits in patients with Parkinson's disease. Remediation and management prospects for these cognitive deficits are based on neuropharmacological and cognitive rehabilitation approaches.Copyright © 2010 Elsevier Ltd. All rights reserved.
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Functional magnetic resonance imaging (fMRI) has been used to study the neural bases of cognitive deficits in Parkinson's disease for several years. Traditionally, task-based fMRI has been applied to study specific cognitive functions, providing information on disease-related alterations and regarding the physiological bases of normal cognition, the dopaminergic system, and the frontostriatal circuits. More recently, functional connectivity techniques using resting-state fMRI data have been developed. Unconstrained by specific cognitive tasks, these techniques allow assessing whole-brain patterns of connectivity believed to be useful proxies for the underlying functional architecture of the brain. These methods have shown that different types of Parkinson's disease-related cognitive deficits are associated with patterns of altered connectivity within and between resting-state intrinsic connectivity networks. Although methodological standardization and the vulnerability of fMRI techniques to artifacts mandate further technical refinement, early studies provide encouraging results regarding the potential of fMRI-derived parameters for the ultimate goal of individual-subject classification.© 2019 Elsevier Inc. All rights reserved.
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