Functional connectivity in cortical regions in dementia with Lewy bodies and Alzheimer's disease

Kenny, Eva; Blamire, Andrew M.; Firbank, Michael; O’Brien, John T.

doi:10.1093/brain/awr327

Cited by 102 publications

(109 citation statements)

References 68 publications

(103 reference statements)

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“…Similarly, previous studies reported either decreased [23], spared [24], or less impaired [25, 26] connectivity across DMN nodes during resting state in DLB patients compared to AD patients. Finally, regarding DMN functional connectivity in relation to other networks during the resting state, Galvin et al [27] found increased connectivity between the precuneus (a core region of the DMN) and regions in the dorsal attention network (DAN), along with decreased connectivity between the precuneus and the frontoparietal executive control networks and the visual cortices in DLB patients.…”

Section: Introductionsupporting

confidence: 64%

Functional Disconnectivity during Inter-Task Resting State in Dementia with Lewy Bodies

Chabran

Roquet

Gounot

et al. 2018

Dement Geriatr Cogn Disord

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Aims: Limited research has been done on the functional connectivity in visuoperceptual regions in dementia with Lewy bodies (DLB) patients. This study aimed to investigate the functional connectivity differences between a task condition and an inter-task resting state condition within a visuoperceptual paradigm, in DLB patients compared with Alzheimer disease (AD) patients and healthy elderly control subjects. Methods: Twenty-six DLB, 29 AD, and 22 healthy subjects underwent a detailed clinical and neuropsychological examination along with a functional MRI during the different conditions of a visuoperceptual paradigm. Functional images were analyzed using group-level spatial independent component analysis and seed-based connectivity analyses. Results: While the DLB patients scored well and did not differ from the control and AD groups in terms of functional activity and connectivity during the task conditions, they showed decreased functional connectivity in visuoperceptual regions during the resting state condition, along with a temporal impairment of the default-mode network activity. Functional connectivity disturbances were also found within two attentional-executive networks and between these networks and visuoperceptual regions. Conclusion: We found a specific functional profile in the switching between task and resting state conditions in DLB patients. This result could help better characterize functional impairments in DLB and their contribution to several core symptoms of this pathology such as visual hallucinations and cognitive fluctuations.

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Section: Introductionsupporting

confidence: 64%

Functional Disconnectivity during Inter-Task Resting State in Dementia with Lewy Bodies

Chabran

Roquet

Gounot

et al. 2018

Dement Geriatr Cogn Disord

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“…Further support for the possible role of these networks in VH has come from a number of fMRI studies where the DMN was consistently found to be hyperactive or normally active in patients affected by DLB [144] or PD [145] at variance with its observed hypoactivation in AD. Specifically Sauer et al [146] noted that DMN activity is increased in patients with DLB in comparison with AD patients [147] and Rektorova et al [144] that DMN activity in PD is not reduced during engagement in a visual recognition task.…”

Section: Further Modelsmentioning

confidence: 99%

Visual Hallucinations in PD and Lewy Body Dementias: Old and New Hypotheses

Onofrj

Taylor

Monaco

et al. 2013

Behavioural Neurology

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Abstract. Visual Hallucinations (VH) are a common non-motor symptom of Parkinson's Disease (PD) and the Lewy body dementias (LBD) of Parkinson's disease with dementia (PDD) and Dementia with Lewy Bodies (DLB). The origin of VH in PD and LBD is debated: earlier studies considered a number of different possible mechanisms underlying VH including visual disorders, Rapid Eye Movement (REM) Sleep Intrusions, dysfunctions of top down or bottom up visual pathways, and neurotransmitter imbalance. More recently newer hypotheses introduce, among the possible mechanisms of VH, the role of attention networks (ventral and dorsal) and of the Default Mode Network (DMN) a network that is inhibited during attentional tasks and becomes active during rest and self referential imagery. Persistent DMN activity during active tasks with dysfunctional imbalance of dorsal and ventral attentional networks represents a new hypothesis on the mechanism of VH. We review the different methods used to classify VH and discuss reports supporting or challenging the different hypothetical mechanisms of VH.

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“…It now appears that, despite some variation in findings, most of the existing research has implicated midline structures, for example, medial frontal cortex, PCC, precuneus, and the mesial temporal lobes. These structures also appear involved in the neuropathology of other neurodegenerative disorders, including AD (Greicius et al, 2004) and dementia with Lewy bodies (Kenny et al, 2012), which makes it likely that the FC changes observed in patients with TLE may be related to network-level changes not specific to epilepsy. We relied on a relatively novel approach, task-regressed fMRI, whose reliability and validity has been supported in past MRI research.…”

mentioning

confidence: 99%

Functional Connectivity of the Hippocampus in Temporal Lobe Epilepsy: Feasibility of a Task-Regressed Seed-Based Approach

et al. 2013

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Objective: Resting-state functional connectivity (FC) has revealed marked network dysfunction in patients with temporal lobe epilepsy (TLE) compared to healthy controls. However, the nature and the location of these changes have not been fully elucidated nor confirmed by other methodologies. We assessed the presence of hippocampal FC changes in TLE based on the low frequency residuals of task-related functional magnetic resonance imaging data after the removal of task-related activation [i.e., task-regressed functional connectivity MRI (fcMRI)]. Method: We employed a novel, task-regressed approach to quantify hippocampal FC, and compare hippocampal FC in 17 patients with unilateral TLE (9 left) with 17 healthy controls. Results: Our results suggest widespread FC reductions in the mesial cortex associated with the default mode network (DMN), and some local FC increases in the lateral portions of the right hemisphere. We found more pronounced FC decreases in the left hemisphere than in the right, and these FC decreases were greatest in patients with left TLE. Moreover, the FC reductions observed between the hippocampus and posterior cingulate, inferior parietal, paracentral regions are in agreement with previous resting state studies. Conclusions: Consistent with the existing literature, FC reductions in TLE appear widespread with prominent reductions in the medial portion of the DMN. Our data expand the literature by demonstrating that reductions in FC may be greatest in the left hemisphere and in patients with left TLE. Overall, our findings suggest that task-regressed FC is a viable alternative to resting state and that future studies may extract similar information on network connectivity from already existing datasets.

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Functional connectivity in cortical regions in dementia with Lewy bodies and Alzheimer's disease

Cited by 102 publications

References 68 publications

Functional Disconnectivity during Inter-Task Resting State in Dementia with Lewy Bodies

Functional Disconnectivity during Inter-Task Resting State in Dementia with Lewy Bodies

Visual Hallucinations in PD and Lewy Body Dementias: Old and New Hypotheses

Functional Connectivity of the Hippocampus in Temporal Lobe Epilepsy: Feasibility of a Task-Regressed Seed-Based Approach

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