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fMRI stroke

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https://www.readbyqxmd.com/read/29782329/longitudinal-fmri-study-of-language-recovery-after-a-left-hemispheric-ischemic-stroke
#1
Rodolphe Nenert, Jane B Allendorfer, Amber M Martin, Christi Banks, Jennifer Vannest, Scott K Holland, Kimberly W Hart, Christopher J Lindsell, Jerzy P Szaflarski
BACKGROUND: Recovery from stroke-induced aphasia is typically protracted and involves complex functional reorganization. The relative contributions of the lesioned and non-lesioned hemispheres to this process have been examined in several cross-sectional studies but longitudinal studies involving several time-points and large numbers of subjects are scarce. OBJECTIVE: The aim of this study was to address the gaps in the literature by longitudinally studying the evolution of post-stroke lateralization and localization of language-related fMRI activation in the first year after single left hemispheric ischemic stroke...
2018: Restorative Neurology and Neuroscience
https://www.readbyqxmd.com/read/29781583/altered-white-matter-connectivity-associated-with-visual-hallucinations-following-occipital-stroke
#2
Sara A Rafique, John R Richards, Jennifer K E Steeves
INTRODUCTION: Visual 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. METHODS: We 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...
May 21, 2018: Brain and Behavior
https://www.readbyqxmd.com/read/29770439/increase-of-frontal-neuronal-activity-in-chronic-neglect-after-training-in-virtual-reality
#3
U Ekman, H Fordell, J Eriksson, N Lenfeldt, A Wåhlin, A Eklund, J Malm
OBJECTIVES: A third of patients with stroke acquire spatial neglect associated with poor rehabilitation outcome. New effective rehabilitation interventions are needed. Scanning training combined with multisensory stimulation to enhance the rehabilitation effect is suggested. In accordance, we have designed a virtual-reality based scanning training that combines visual, audio and sensori-motor stimulation called RehAtt® . Effects were shown in behavioural tests and activity of daily living...
May 16, 2018: Acta Neurologica Scandinavica
https://www.readbyqxmd.com/read/29766355/early-functional-mri-activation-predicts-motor-outcome-after-ischemic-stroke-a-longitudinal-multimodal-study
#4
Juan Du, Fang Yang, Zhiqiang Zhang, Jingze Hu, Qiang Xu, Jianping Hu, Fanyong Zeng, Guangming Lu, Xinfeng Liu
An accurate prediction of long term outcome after stroke is urgently required to provide early individualized neurorehabilitation. This study aimed to examine the added value of early neuroimaging measures and identify the best approaches for predicting motor outcome after stroke. This prospective study involved 34 first-ever ischemic stroke patients (time since stroke: 1-14 days) with upper limb impairment. All patients underwent baseline multimodal assessments that included clinical (age, motor impairment), neurophysiological (motor-evoked potentials, MEP) and neuroimaging (diffusion tensor imaging and motor task-based fMRI) measures, and also underwent reassessment 3 months after stroke...
May 15, 2018: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/29696239/effects-and-mechanism-of-the-hect-study-hybrid-exercise-cognitive-trainings-in-mild-ischemic-stroke-with-cognitive-decline-fmri-for-brain-plasticity-biomarker-and-behavioral-analysis
#5
Ting-Ting Yeh, Ku-Chou Chang, Ching-Yi Wu, Ya-Yun Lee, Po-Yu Chen, Jen-Wen Hung
Purpose: Cognitive decline after stroke is highly associated with functional disability. Empirical evidence shows that exercise combined cognitive training may induce neuroplastic changes that modulate cognitive function. However, it is unclear whether hybridized exercise-cognitive training can facilitate cortical activity and physiological outcome measures and further influence on the cognitive function after stroke. This study will investigate the effects of two hybridized exercise-cognitive trainings on brain plasticity, physiological biomarkers and behavioral outcomes in stroke survivors with cognitive decline...
March 2018: Contemporary Clinical Trials Communications
https://www.readbyqxmd.com/read/29671156/alteration-and-role-of-interhemispheric-and-intrahemispheric-connectivity-in-motor-network-after-stroke
#6
Jungsoo Lee, Eunhee Park, Ahee Lee, Won Hyuk Chang, Dae-Shik Kim, Yun-Hee Kim
This study investigated local and global changes in the motor network using longitudinal resting-state functional magnetic resonance imaging (rs-fMRI). Motor impairment was measured in 81 stroke patients using Fugl-Meyer assessment on the same day as rs-fMRI acquisition at both 2 weeks and 3 months post-stroke. The relationships between network measures and motor function scores were assessed. With regard to local connectivity, interhemispheric connectivity was noticeably altered at each time point. Interhemispheric connectivity was also related to residual motor function and improvement in motor function...
April 18, 2018: Brain Topography
https://www.readbyqxmd.com/read/29666636/modulating-brain-connectivity-by-simultaneous-dual-mode-stimulation-over-bilateral-primary-motor-cortices-in-subacute-stroke-patients
#7
Jungsoo Lee, Eunhee Park, Ahee Lee, Won Hyuk Chang, Dae-Shik Kim, Yong-Il Shin, Yun-Hee Kim
Repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) has been used for the modulation of stroke patients' motor function. Recently, more challenging approaches have been studied. In this study, simultaneous stimulation using both rTMS and tDCS (dual-mode stimulation) over bilateral primary motor cortices (M1s) was investigated to compare its modulatory effects with single rTMS stimulation over the ipsilesional M1 in subacute stroke patients. Twenty-four patients participated; 12 participants were assigned to the dual-mode stimulation group while the other 12 participants were assigned to the rTMS-only group...
2018: Neural Plasticity
https://www.readbyqxmd.com/read/29541576/a-comparison-of-functional-and-tractography-based-networks-in-cerebral-small-vessel-disease
#8
Andrew J Lawrence, Daniel J Tozer, Emmanuel A Stamatakis, Hugh S Markus
Objective: MRI measures of network integrity may be useful disease markers in cerebral small vessel disease (SVD). We compared the sensitivity and reproducibility of MRI derived structural and functional network measures in healthy controls and SVD subjects. Methods: Diffusion tractography and resting state fMRI were used to create connectivity matrices from 26 subjects with symptomatic MRI confirmed lacunar stroke and 19 controls. Matrices were constructed at multiple scales based on a multi-resolution cortical atlas and at multiple thresholds for the matrix density...
2018: NeuroImage: Clinical
https://www.readbyqxmd.com/read/29527477/removal-of-artifacts-from-resting-state-fmri-data-in-stroke
#9
Grigori Yourganov, Julius Fridriksson, Brielle Stark, Christopher Rorden
We examined the effect of lesion on the resting-state functional connectivity in chronic post-stroke patients. We found many instances of strong correlations in BOLD signal measured at different locations within the lesion, making it hard to distinguish from the connectivity between intact and strongly connected regions. Regression of the mean cerebro-spinal fluid signal did not alleviate this problem. The connectomes computed by exclusion of lesioned voxels were not good predictors of the behavioral measures...
2018: NeuroImage: Clinical
https://www.readbyqxmd.com/read/29526647/neural-mechanisms-of-two-different-verbal-working-memory-tasks-a-vlsm-study
#10
M V Ivanova, O Dragoy, S V Kuptsova, S Yu Akinina, A G Petrushevskii, O N Fedina, A Turken, V M Shklovsky, N F Dronkers
Currently, a distributed bilateral network of frontal-parietal areas is regarded as the neural substrate of working memory (WM), with the verbal WM network being more left-lateralized. This conclusion is based primarily on functional magnetic resonance imaging (fMRI) data that provides correlational evidence for brain regions involved in a task. However, fMRI cannot differentiate the areas that are fundamentally required for performing a task. These data can only come from brain-injured individuals who fail the task after the loss of specific brain areas...
March 8, 2018: Neuropsychologia
https://www.readbyqxmd.com/read/29504985/effectiveness-and-neural-mechanisms-of-home-based-telerehabilitation-in-patients-with-stroke-based-on-fmri-and-dti-a-study-protocol-for-a-randomized-controlled-trial
#11
RANDOMIZED CONTROLLED TRIAL
Jing Chen, Mingli Liu, Dalong Sun, Yan Jin, Tianrao Wang, Chuancheng Ren
BACKGROUND: Stroke is one of leading diseases causing adult death and disability worldwide. Home-based telerehabilitation has become a novel approach for stroke patients as effective as conventional rehabilitation, and more convenient and economical than conventional rehabilitation. However, there is no study assessing the mechanism of home-based telerehabilitation in promoting motor recovery among stroke patients with hemiplegic. AIMS: This study is designed to determine the efficacy and explore the mechanism of motor recovery after home-based telerehabilitation in stroke patients with motor deficits...
January 2018: Medicine (Baltimore)
https://www.readbyqxmd.com/read/29490535/neurofunctional-changes-after-a-single-mirror-therapy-intervention-in-chronic-ischemic-stroke
#12
Morgana M Novaes, Fernanda Palhano-Fontes, Andre Peres, Kelley Mazzetto-Betti, Maristela Pelicioni, Kátia C Andrade, Antonio Carlos Dos Santos, Octavio Pontes-Neto, Draulio Araujo
BACKGROUND: Mirror therapy (MT) is becoming an alternative rehabilitation strategy for various conditions, including stroke. Although recent studies suggest the positive benefit of MT in chronic stroke motor recovery, little is known about its neural mechanisms. PURPOSE: To identify functional brain changes induced by a single MT intervention in ischemic stroke survivors, assessed by both transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI)...
March 20, 2018: International Journal of Neuroscience
https://www.readbyqxmd.com/read/29414460/re-emergence-of-modular-brain-networks-in-stroke-recovery
#13
Joshua S Siegel, Benjamin A Seitzman, Lenny E Ramsey, Mario Ortega, Evan M Gordon, Nico U F Dosenbach, Steven E Petersen, Gordon L Shulman, Maurizio Corbetta
Studies of stroke have identified local reorganization in perilesional tissue. However, because the brain is highly networked, strokes also broadly alter the brain's global network organization. Here, we assess brain network structure longitudinally in adult stroke patients using resting state fMRI. The topology and boundaries of cortical regions remain grossly unchanged across recovery. In contrast, the modularity of brain systems i.e. the degree of integration within and segregation between networks, was significantly reduced sub-acutely (n = 107), but partially recovered by 3 months (n = 85), and 1 year (n = 67)...
April 2018: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/29414287/symbol-digit-modalities-test-adaptation-for-magnetic-resonance-imaging-environment-a-systematic-review-and-meta-analysis
#14
REVIEW
P H R Silva, C T Spedo, A A Barreira, R F Leoni
BACKGROUND: The Symbol Digit Modalities Test (SDMT) is widely used for cognitive evaluation of information processing speed (IPS), required in many cognitive operations. Despite being unspecific for different neurological disorders, it is sensitive to assess impaired performance related to stroke, Parkinson's disease, traumatic brain injury, and multiple sclerosis. However, in addition to evaluate the presence and severity of IPS impairment, it is of interest to determine the localization and integration of brain regions responsible for the functions assessed by the SDMT...
February 2018: Multiple Sclerosis and related Disorders
https://www.readbyqxmd.com/read/29373162/altered-functional-connectivity-in-post-ischemic-stroke-depression-a-resting-state-functional-magnetic-resonance-imaging-study
#15
Peiyao Zhang, Jing Wang, Qin Xu, Zheng Song, Jianping Dai, Jun Wang
OBJECTIVE: In previous studies, post-stroke depression (PSD) was found to be related to stroke characteristics as well as social and psychological factors. This study identified altered functional connectivity (FC) in patients with PSD at the subacute phase in three brain networks: default mood network (DMN), cognitive control network (CCN), and affective network (AN). The correlation between FC and the severity of PSD was investigated. MATERIALS AND METHODS: Resting-state functional magnetic resonance image (rs-fMRI) was performed on 26 PSD patients (6 females), 24 stroke patients without depression (5 females), and 24 age-matched normal controls (6 females) all aged 40-75 years...
March 2018: European Journal of Radiology
https://www.readbyqxmd.com/read/29359375/a-scalable-multi-resolution-spatio-temporal-model-for-brain-activation-and-connectivity-in-fmri-data
#16
Stefano Castruccio, Hernando Ombao, Marc G Genton
Functional Magnetic Resonance Imaging (fMRI) is a primary modality for studying brain activity. Modeling spatial dependence of imaging data at different spatial scales is one of the main challenges of contemporary neuroimaging, and it could allow for accurate testing for significance in neural activity. The high dimensionality of this type of data (on the order of hundreds of thousands of voxels) poses serious modeling challenges and considerable computational constraints. For the sake of feasibility, standard models typically reduce dimensionality by modeling covariance among regions of interest (ROIs)-coarser or larger spatial units-rather than among voxels...
January 22, 2018: Biometrics
https://www.readbyqxmd.com/read/29341020/mri-in-the-study-of-animal-models-of-stroke
#17
Pedro Ramos-Cabrer, Daniel Padro
Stroke consists of the loss of cerebral functions resulting from the interruption of blood supply to a region of the brain, and represents the second cause of death and the leading cause of major disability in adults in Europe. Stroke is a very active field of research at preclinical and clinical levels, and Magnetic Resonance Imaging (MRI) is one of the most powerful tools that scientist and clinicians have for the study of the onset, evolution and consequences of this devastating disease, as well as for the monitoring of the success of available treatments, or for the development of novel therapeutic strategies...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29338310/therapy-induced-plasticity-in-chronic-aphasia-is-associated-with-behavioral-improvement-and-time-since-stroke
#18
Priya Santhanam, E Susan Duncan, Steven L Small
Cortical reorganization after stroke is thought to underlie functional improvement. Patterns of reorganization may differ depending on the amount of time since the stroke or the degree of improvement. We investigated these issues in a study of brain connectivity changes with aphasia therapy. Twelve individuals with chronic aphasia participated in a 6-week trial of imitation-based speech therapy. We assessed improvement on a repetition test and analyzed effective connectivity during functional magnetic resonance imaging of a speech observation task before and after therapy...
March 23, 2018: Brain Connectivity
https://www.readbyqxmd.com/read/29329693/bold-fmri-signal-in-stroke-patients-and-its-importance-for-prognosis-in-the-subacute-disease-period-preliminary-report
#19
Anetta Lasek-Bal, Joanna Kidoń, Monika Błaszczyszyn, Bartłomiej Stasiów, Amadeusz Żak
Functional magnetic resonance imaging (fMRI) allows for the assessment of neuronal activity through the blood-level-dependent signal. The purpose of study was to evaluate the pattern of brain activity in fMRI in patients with ischemic stroke and to assess the potential relationship between the activity pattern and the neurological/functional status. METHODS: The fMRI was performed in patients up to 4th day of stroke. All the patients were analyzed according to NIHSS on 1st day and mRankin scale on 14th day of stroke, followed by analyzing of fMRI signal...
December 24, 2017: Neurologia i Neurochirurgia Polska
https://www.readbyqxmd.com/read/29223933/task-based-and-resting-state-fmri-reveal-compensatory-network-changes-following-damage-to-left-inferior-frontal-gyrus
#20
Glyn P Hallam, Hannah E Thompson, Mark Hymers, Rebecca E Millman, Jennifer M Rodd, Matthew A Lambon Ralph, Jonathan Smallwood, Elizabeth Jefferies
Damage to left inferior prefrontal cortex in stroke aphasia is associated with semantic deficits reflecting poor control over conceptual retrieval, as opposed to loss of knowledge. However, little is known about how functional recruitment within the semantic network changes in patients with executive-semantic deficits. The current study acquired functional magnetic resonance imaging (fMRI) data from 14 patients with semantic aphasia, who had difficulty with flexible semantic retrieval following left prefrontal damage, and 16 healthy age-matched controls, allowing us to examine activation and connectivity in the semantic network...
February 2018: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
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