Hippocampal dysfunction is associated with memory impairment in multiple sclerosis: A volumetric and functional connectivity study

Torre, Julio Alberto González; Cruz-Gómez, Álvaro Javier; Belenguer, Antonio; Sanchis‐Segura, Carles; Ávila, César; Forn, Cristina

doi:10.1177/1352458516688349

Cited by 41 publications

(34 citation statements)

References 22 publications

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“…Other brain regions that show positive correlations between cognitive performance and connectivity in MS are the medial prefrontal cortex and the frontal pole ( 35 ), the left insula ( 48 ), as well as the hippocampus ( 82 , 111 ). However, increased FC of the right posterior hippocampus to the rest of the brain was elsewhere described as a main correlate of mnestic impairment ( 112 ).…”

Section: Overview Of Selected Literaturementioning

confidence: 95%

Functional Connectivity in Multiple Sclerosis: Recent Findings and Future Directions

et al. 2018

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Multiple sclerosis is a debilitating disorder resulting from scattered lesions in the central nervous system. Because of the high variability of the lesion patterns between patients, it is difficult to relate existing biomarkers to symptoms and their progression. The scattered nature of lesions in multiple sclerosis offers itself to be studied through the lens of network analyses. Recent research into multiple sclerosis has taken such a network approach by making use of functional connectivity. In this review, we briefly introduce measures of functional connectivity and how to compute them. We then identify several common observations resulting from this approach: (a) high likelihood of altered connectivity in deep-gray matter regions, (b) decrease of brain modularity, (c) hemispheric asymmetries in connectivity alterations, and (d) correspondence of behavioral symptoms with task-related and task-unrelated networks. We propose incorporating such connectivity analyses into longitudinal studies in order to improve our understanding of the underlying mechanisms affected by multiple sclerosis, which can consequently offer a promising route to individualizing imaging-related biomarkers for multiple sclerosis.

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Section: Overview Of Selected Literaturementioning

confidence: 95%

Functional Connectivity in Multiple Sclerosis: Recent Findings and Future Directions

et al. 2018

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“…Anatomical T1-weighted images were processed by Freesurfer 5.3, a fully automated image analysis software for the volumetric segmentation of hippocampal subfields ( http://surfer.nmr.mgh.harvard.edu ). Specific details of this procedure are available in previous publications 49 . Briefly, this procedure includes motion correction, removal of non-brain, automated Talairach transformation, segmentation of the subcortical white matter and deep gray matter structures, intensity normalization, tessellation of the gray matter/white matter boundary, automated topology correction, and surface deformation following gradients to place the gray/white and gray/cerebrospinal fluid borders optimally at the location where the greatest shift in intensity defines the transition to the other tissue type.…”

Section: Methodsmentioning

confidence: 99%

“…The process also segments both the hippocampi of each subject into eight subfields, including the cornu ammonis 1 (CA1), cornu ammonis 2–3 (CA2-3), cornu ammonis 4-dentade gyrus (CA4-DG), subiculum, presubiculum, fimbria, hippocampal fissure, and posterior hippocampus. The technical details of these procedures have been described elsewhere 49 .…”

Section: Methodsmentioning

confidence: 99%

Learning and Memory Impairments in Patients with Minimal Hepatic Encephalopathy are Associated with Structural and Functional Connectivity Alterations in Hippocampus

García‐García

Cruz-Gómez

Urios

et al. 2018

Sci Rep

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Patients with minimal hepatic encephalopathy (MHE) show mild cognitive impairment associated with alterations in attentional and executive networks. There are no studies evaluating the relationship between memory in MHE and structural and functional connectivity (FC) changes in the hippocampal system. This study aimed to evaluate verbal learning and long-term memory in cirrhotic patients with (C-MHE) and without MHE (C-NMHE) and healthy controls. We assessed the relationship between alterations in memory and the structural integrity and FC of the hippocampal system. C-MHE patients showed impairments in learning, long-term memory, and recognition, compared to C-NMHE patients and controls. Cirrhotic patients showed reduced fimbria volume compared to controls. Larger volumes in hippocampus subfields were related to better memory performance in C-NMHE patients and controls. C-MHE patients presented lower FC between the L-presubiculum and L-precuneus than C-NMHE patients. Compared to controls, C-MHE patients had reduced FC between L-presubiculum and subiculum seeds and bilateral precuneus, which correlated with cognitive impairment and memory performance. Alterations in the FC of the hippocampal system could contribute to learning and long-term memory impairments in C-MHE patients. This study demonstrates the association between alterations in learning and long-term memory and structural and FC disturbances in hippocampal structures in cirrhotic patients.

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“…Hippocampal involvement in MS has also been demonstrated using fMRI techniques, both with hippocampus-related active fMRI tasks and by analyzing resting state -(RS) functional connectivity (FC). [45][46][47][48] Different patterns of activation (increased activation, decreased activation, or more recently, increased deactivation) 49 and FC (increased RS FC or decreased RS FC) have been shown in patients with and without cognitive deficits or depression (Appendix). 50,51 These fMRI abnormalities are seen prior to the development of atrophy and hippocampusrelated cognitive deficits, suggesting that they may be an early indicator of hippocampal dysfunction.…”

Section: Imaging Hippocampal Damage In Ms Using Mrimentioning

confidence: 99%

“…50,51 These fMRI abnormalities are seen prior to the development of atrophy and hippocampusrelated cognitive deficits, suggesting that they may be an early indicator of hippocampal dysfunction. [45][46][47]…”

Section: Imaging Hippocampal Damage In Ms Using Mrimentioning

confidence: 99%

The hippocampus in multiple sclerosis

Rocca

Barkhof

Luca

et al. 2018

The Lancet Neurology

108

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Some of the clinical manifestations of multiple sclerosis, such as memory impairment and depression, are, at least partly, related to involvement of the hippocampus. Pathological studies have shown extensive demyelination, neuronal damage, and synaptic abnormalities in the hippocampus of patients with multiple sclerosis, and improvements in MRI technology have provided novel ways to assess hippocampal involvement in vivo. It is now accepted that clinical manifestations related to the hippocampus are due not only to focal hippocampal damage, but also to disconnection of the hippocampus from several brain networks. Evidence suggests anatomical and functional subspecialisation of the different hippocampal subfields, resulting in variability between regions in the extent to which damage and repair occur. The hippocampus also has important roles in plasticity and neurogenesis, both of which potentially contribute to functional preservation and restoration. These findings underline the importance of evaluation of the hippocampus not only to improve understanding of the clinical manifestations of multiple sclerosis, but also as a potential future target for treatment.

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Hippocampal dysfunction is associated with memory impairment in multiple sclerosis: A volumetric and functional connectivity study

Cited by 41 publications

References 22 publications

Functional Connectivity in Multiple Sclerosis: Recent Findings and Future Directions

Functional Connectivity in Multiple Sclerosis: Recent Findings and Future Directions

Learning and Memory Impairments in Patients with Minimal Hepatic Encephalopathy are Associated with Structural and Functional Connectivity Alterations in Hippocampus

The hippocampus in multiple sclerosis

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