Enhanced Effective Connectivity in Mild Occipital Stroke Patients With Hemianopia

Guo, Xiaoli; Jin, Zheng; Feng, Xinyang; Tong, Shanbao

doi:10.1109/tnsre.2014.2325601

Cited by 18 publications

(14 citation statements)

References 68 publications

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“…Increased ipsilesional tracts in the patient (Figure a) suggest recruitment of redundant/association neurons. Global overconnectivity is observed in patients with hemianopia following occipital stroke, with greater node strength in ipsilesional temporal and orbitofrontal areas as well as the contralesional visual association cortex (Guo, Jin, Feng, & Tong, ).…”

Section: Discussionmentioning

confidence: 99%

Altered white matter connectivity associated with visual hallucinations following occipital stroke

2018

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IntroductionVisual hallucinations that arise following vision loss stem from aberrant functional activity in visual cortices and an imbalance of activity across associated cortical and subcortical networks subsequent to visual pathway damage. We sought to determine if structural changes in white matter connectivity play a role in cases of chronic visual hallucinations associated with visual cortical damage.MethodsWe performed diffusion tensor imaging (DTI) and probabilistic fiber tractography to assess white matter connectivity in a patient suffering from continuous and disruptive phosphene (simple) visual hallucinations for more than 2 years following right occipital stroke. We compared these data to that of healthy age‐matched controls.ResultsProbabilistic tractography to reconstruct white matter tracts suggests regeneration of terminal fibers of the ipsilesional optic radiations in the patient. However, arrangement of the converse reconstruction of these tracts, which were seeded from the ipsilesional visual cortex to the intrahemispheric lateral geniculate body, remained disrupted. We further observed compromised structural characteristics, and changes in diffusion (measured using diffusion tensor indices) of white matter tracts in the patient connecting the visual cortex with frontal and temporal regions, and also in interhemispheric connectivity between visual cortices.ConclusionsCortical remapping and the disruption of communication between visual cortices and remote regions are consistent with our previous functional magnetic resonance imaging (fMRI) data showing imbalanced functional activity of the same regions in this patient (Rafique et al, 2016, Neurology, 87, 1493–1500). Long‐term adaptive and disruptive changes in white matter connectivity may account for the rare nature of cases presenting with chronic and continuous visual hallucinations.

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Section: Discussionmentioning

confidence: 99%

Altered white matter connectivity associated with visual hallucinations following occipital stroke

2018

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“…This neuroplasticity occurs via 5-HT signaling to induce neurotrophins and reduce interneuronal inhibition in the visual cortex. Similarly, SSRI treatment of stroke patients increases visual recovery and is associated with reorganization of visual cortex connectivity 14 , 15 . In some but not all studies, treatment of non-depressed stroke patients with SSRIs improves recovery of motor function 16 – 18 .…”

Section: Introductionmentioning

confidence: 99%

Fluoxetine-induced recovery of serotonin and norepinephrine projections in a mouse model of post-stroke depression

et al. 2020

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Chronic treatment with fluoxetine (FLX) is required for its antidepressant effects, but the role of serotonin (5-HT) axonal plasticity in FLX action is unknown. To address this, we examined mice with a stroke in the left medial prefrontal cortex (mPFC) resulting in persistent anxiety-like and depression-like behaviors and memory deficits as a model of post-stroke depression. Chronic treatment with FLX (but not exercise) completely reversed the behavioral phenotype and partially reversed changes in FosB-labeled cells in the mPFC, nucleus accumbens, septum, hippocampus, basolateral amygdala (BLA), and dorsal raphe. In these regions, 5-HT or norepinephrine (NE) innervation was quantified by staining for 5-HT or NE transporters, respectively. 5-HT synapses and synaptic triads were identified as synaptophysin-stained sites on 5-HT axons located proximal to gephyrin-stained or PSD95-stained spines. A week after stroke, 5-HT innervation was greatly reduced at the stroke site (left cingulate gyrus (CG) of the mPFC) and the left BLA. Chronically, 5-HT and NE innervation was reduced at the left CG, nucleus accumbens, and BLA, with no changes in other regions. In these areas, pre-synaptic and post-synaptic 5-HT synapses and triads to inhibitory (gephyrin+) sites were reduced, while 5-HT contacts at excitatory (PSD95+) sites were reduced in the CG and prelimbic mPFC. Chronic FLX, but not exercise, reversed these reductions in 5-HT innervation but incompletely restored NE projections. Changes in 5-HT innervation were verified using YFP staining in mice expressing YFP-tagged channelrhodopsin in 5-HT neurons. Thus, FLX-induced 5-HT axonal neuroplasticity of forebrain projections may help mediate recovery from brain injury.

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“…Alterations in brain network properties, such as efficiency and clustering coefficient, are also observed in aging [ 15 , 16 , 25 , 26 ]. However, the consistency of the graph properties of brain networks within a group is sometimes not very satisfactory [ 27 ]. Some scientists cannot obtain statistically significant differences in some graph properties between different groups.…”

Section: Introductionmentioning

confidence: 99%

A Novel Brain Network Construction Method for Exploring Age-Related Functional Reorganization

Wang

et al. 2016

Computational Intelligence and Neuroscience

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The human brain undergoes complex reorganization and changes during aging. Using graph theory, scientists can find differences in topological properties of functional brain networks between young and elderly adults. However, these differences are sometimes significant and sometimes not. Several studies have even identified disparate differences in topological properties during normal aging or in age-related diseases. One possible reason for this issue is that existing brain network construction methods cannot fully extract the “intrinsic edges” to prevent useful signals from being buried into noises. This paper proposes a new subnetwork voting (SNV) method with sliding window to construct functional brain networks for young and elderly adults. Differences in the topological properties of brain networks constructed from the classic and SNV methods were consistent. Statistical analysis showed that the SNV method can identify much more statistically significant differences between groups than the classic method. Moreover, support vector machine was utilized to classify young and elderly adults; its accuracy, based on the SNV method, reached 89.3%, significantly higher than that with classic method. Therefore, the SNV method can improve consistency within a group and highlight differences between groups, which can be valuable for the exploration and auxiliary diagnosis of aging and age-related diseases.

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Enhanced Effective Connectivity in Mild Occipital Stroke Patients With Hemianopia

Cited by 18 publications

References 68 publications

Altered white matter connectivity associated with visual hallucinations following occipital stroke

Altered white matter connectivity associated with visual hallucinations following occipital stroke

Fluoxetine-induced recovery of serotonin and norepinephrine projections in a mouse model of post-stroke depression

A Novel Brain Network Construction Method for Exploring Age-Related Functional Reorganization

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