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https://www.readbyqxmd.com/read/29341006/mapping-functional-connectivity-in-the-rodent-brain-using-electric-stimulation-fmri
#1
Laura Pérez-Cervera, José María Caramés, Luis Miguel Fernández-Mollá, Andrea Moreno, Begoña Fernández, Elena Pérez-Montoyo, David Moratal, Santiago Canals, Jesús Pacheco-Torres
Since its discovery in the early 90s, BOLD signal-based functional Magnetic Resonance Imaging (fMRI) has become a fundamental technique for the study of brain activity in basic and clinical research. Functional MRI signals provide an indirect but robust and quantitative readout of brain activity through the tight coupling between cerebral blood flow and neuronal activation, the so-called neurovascular coupling. Combined with experimental techniques only available in animal models, such as intracerebral micro-stimulation, optogenetics or pharmacogenetics, provides a powerful framework to investigate the impact of specific circuit manipulations on overall brain dynamics...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29334834/mild-jugular-compression-collar-ameliorated-changes-in-brain-activation-of-working-memory-after-one-soccer-season-in-female-high-school-athletes
#2
Weihong Yuan, Jonathan Dudley, Kim Barber-Foss, Jonathan D Ellis, Staci Thomas, Ryan T Galloway, Christopher DiCesare, James Leach, Janet Adams, Thomas Maloney, Brooke Gadd, David Smith, Jeff Epstein, Dustin R Grooms, Kelsey Logan, David R Howell, Mekibib Altaye, Gregory D Myer
Recent neuroimaging studies have suggested that repetitive sub-concussive head impacts, even after only one sport season, may lead to pre- to post-season structural and functional alterations in male high school football athletes. However, data on female atheletes is limited. In the current investigation, we aimed to (1) assess the longitudinal pre- to post-season changes in fMRI of working memory and working memory performance, (2) quantify the association between the pre- to post-season change in fMRI of working memory and the exposure to head impact and working memory performance, and (3) assess whether wearing a neck collar designed to reduce intracranial slosh via mild compression of the jugular veins can ameliorate the changes in fMRI brain activation observed in the non-collar group after a full soccer season...
January 15, 2018: Journal of Neurotrauma
https://www.readbyqxmd.com/read/29331056/exploring-the-advantages-of-multiband-fmri-with-simultaneous-eeg-to-investigate-coupling-between-gamma-frequency-neural-activity-and-the-bold-response-in-humans
#3
Makoto Uji, Ross Wilson, Susan T Francis, Karen J Mullinger, Stephen D Mayhew
We established an optimal combination of EEG recording during sparse multiband (MB) fMRI that preserves high-resolution, whole-brain fMRI coverage while enabling broad-band EEG recordings which are uncorrupted by MRI gradient artefacts (GAs). We first determined the safety of simultaneous EEG recording during MB fMRI. Application of MB factor = 4 produced <1°C peak heating of electrode/hardware during 20 min of GE-EPI data acquisition. However, higher SAR sequences require specific safety testing, with greater heating observed using PCASL with MB factor = 4...
January 13, 2018: Human Brain Mapping
https://www.readbyqxmd.com/read/29325997/reduced-cortical-oxygenation-predicts-a-progressive-decline-of-renal-function-in-patients-with-chronic-kidney-disease
#4
Menno Pruijm, Bastien Milani, Edward Pivin, Agata Podhajska, Bruno Vogt, Matthias Stuber, Michel Burnier
Renal tissue hypoxia is a final pathway in the development and progression of chronic kidney disease (CKD), but whether renal oxygenation predicts renal function decline in humans has not been proven. Therefore, we performed a prospective study and measured renal tissue oxygenation by blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) in 112 patients with CKD, 47 with hypertension without CKD, and 24 healthy control individuals. Images were analyzed with the twelve-layer concentric objects method that divided the renal parenchyma in 12 layers of equal thickness and reports the mean R2* value of each layer (a high R2* corresponds to low oxygenation), along with the change in R2* between layers called the R2* slope...
January 9, 2018: Kidney International
https://www.readbyqxmd.com/read/29285809/investigation-of-the-bold-and-cbv-fmri-responses-to-somatosensory-stimulation-in-awake-marmosets-callithrix-jacchus
#5
Yoshiyuki Hirano, Cecil C Yen, Junjie V Liu, Julie B Mackel, Hellmut Merkle, George C Nascimento, Bojana Stefanovic, Afonso C Silva
Understanding the spatiotemporal features of the hemodynamic response function (HRF) to brain stimulation is essential for the correct application of neuroimaging methods to study brain function. Here, we investigated the spatiotemporal evolution of the blood oxygen level-dependent (BOLD) and cerebral blood volume (CBV) HRF in conscious, awake marmosets (Callithrix jacchus), a New World non-human primate with a lissencephalic brain and with growing use in biomedical research. The marmosets were acclimatized to head fixation and placed in a 7-T magnetic resonance imaging (MRI) scanner...
December 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/29285782/hyperpolarized-13-c-15-n2-urea-t2-relaxation-changes-in-acute-kidney-injury
#6
Christian Østergaard Mariager, Per Mose Nielsen, Haiyun Qi, Steffen Ringgaard, Christoffer Laustsen
PURPOSE: To investigate the correlation between renal ischemia and 13 C-urea T2 relaxation rate in an acute kidney injury (AKI) rat model. METHODS: Six rats subjected to unilateral renal ischemia were investigated. Creatinine clearance, urine output, plasma creatinine as well as blood-urea nitrogen (BUN) values were acquired before and after the procedure. 1 H T2* mapping was acquired using blood oxygenation level dependent (BOLD) MRI and hyperpolarized 13 C-urea T2 mapping was acquired using a 2D golden-angle radial approach...
December 28, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29282320/detection-of-synchronous-brain-activity-in-white-matter-tracts-at-rest-and-under-functional-loading
#7
Zhaohua Ding, Yali Huang, Stephen K Bailey, Yurui Gao, Laurie E Cutting, Baxter P Rogers, Allen T Newton, John C Gore
Functional MRI based on blood oxygenation level-dependent (BOLD) contrast is well established as a neuroimaging technique for detecting neural activity in the cortex of the human brain. While detection and characterization of BOLD signals, as well as their electrophysiological and hemodynamic/metabolic origins, have been extensively studied in gray matter (GM), the detection and interpretation of BOLD signals in white matter (WM) remain controversial. We have previously observed that BOLD signals in a resting state reveal structure-specific anisotropic temporal correlations in WM and that external stimuli alter these correlations and permit visualization of task-specific fiber pathways, suggesting variations in WM BOLD signals are related to neural activity...
December 27, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29277650/macroscale-variation-in-resting-state-neuronal-activity-and-connectivity-assessed-by-simultaneous-calcium-imaging-hemodynamic-imaging-and-electrophysiology
#8
Matthew C Murphy, Kevin C Chan, Seong-Gi Kim, Alberto L Vazquez
Functional imaging of spontaneous activity continues to play an important role in the field of connectomics. The most common imaging signal used for these experiments is the blood-oxygen-level-dependent (BOLD) functional MRI (fMRI) signal, but how this signal relates to spontaneous neuronal activity remains incompletely understood. Genetically encoded calcium indicators represent a promising tool to study this problem, as they can provide brain-wide measurements of neuronal activity compared to point measurements afforded by electrophysiological recordings...
December 22, 2017: NeuroImage
https://www.readbyqxmd.com/read/29277267/placental-baseline-conditions-modulate-the-hyperoxic-bold-mri-response
#9
Marianne Sinding, David A Peters, Sofie S Poulsen, Jens B Frøkjær, Ole B Christiansen, Astrid Petersen, Niels Uldbjerg, Anne Sørensen
OBJECTIVES: Human pregnancies complicated by placental dysfunction may be characterized by a high hyperoxic Blood oxygen level-dependent (BOLD) MRI response. The pathophysiology behind this phenomenon remains to be established. The aim of this study was to evaluate whether it is associated with altered placental baseline conditions, including a lower oxygenation and altered tissue morphology, as estimated by the placental transverse relaxation time (T2*). METHOD: We included 49 normal pregnancies (controls) and 13 pregnancies complicated by placental dysfunction (cases), defined by a birth weight < 10th percentile in combination with placental pathological signs of vascular malperfusion...
January 2018: Placenta
https://www.readbyqxmd.com/read/29246201/multiparametric-functional-magnetic-resonance-imaging-for-evaluation-of-hepatic-warm-ischemia-reperfusion-injury-in-a-rabbit-model
#10
Qian Ji, Zhi Qiang Chu, Tao Ren, Shi Chao Xu, Long Jiang Zhang, Wen Shen, Guang Ming Lu
BACKGROUND: To assess the feasibility of noninvasive and quantitative evaluation of hepatic pathophysiological changes in rabbit hepatic warm ischemia-reperfusion injury (WIRI) models by using intravoxel incoherent motion (IVIM), diffusion tensor imaging (DTI) and blood oxygen level dependent (BOLD) MRI. METHODS: Twenty rabbits were randomly divided into hepatic WIRI model group and sham-operation group (n = 10 for each group). Hepatic WIRI was induced in rabbit by occluding hepatic inflow for 30 min and reperfusion for 6 h...
December 15, 2017: BMC Gastroenterology
https://www.readbyqxmd.com/read/29226283/improving-functional-mri-registration-using-whole-brain-functional-correlation-tensors
#11
Yujia Zhou, Pew-Thian Yap, Han Zhang, Lichi Zhang, Qianjin Feng, Dinggang Shen
Population studies of brain function with resting-state functional magnetic resonance imaging (rs-fMRI) largely rely on the accurate inter-subject registration of functional areas. This is typically achieved through registration of the corresponding T1-weighted MR images with more structural details. However, accumulating evidence has suggested that such strategy cannot well-align functional regions which are not necessarily confined by the anatomical boundaries defined by the T1-weighted MR images. To mitigate this problem, various registration algorithms based directly on rs-fMRI data have been developed, most of which have utilized functional connectivity (FC) as features for registration...
September 2017: Medical Image Computing and Computer-assisted Intervention: MICCAI ..
https://www.readbyqxmd.com/read/29217405/a-novel-perspective-to-calibrate-temporal-delays-in-cerebrovascular-reactivity-using-hypercapnic-and-hyperoxic-respiratory-challenges
#12
Allen A Champagne, Alex A Bhogal, Nicole S Coverdale, Clarisse I Mark, Douglas J Cook
Redistribution of blood flow across different brain regions, arising from the vasoactive nature of hypercapnia, can introduce errors when examining cerebrovascular reactivity (CVR) response delays. In this study, we propose a novel analysis method to characterize hemodynamic delays in the blood oxygen level dependent (BOLD) response to hypercapnia, and hyperoxia, as a way to provide insight into transient differences in vascular reactivity between cortical regions, and across tissue depths. A pseudo-continuous arterial spin labeling sequence was used to acquire BOLD and cerebral blood flow simultaneously in 19 healthy adults (12 F; 20 ± 2 years) during boxcar CO2 and O2 gas inhalation paradigms...
December 4, 2017: NeuroImage
https://www.readbyqxmd.com/read/29208571/using-multi-echo-simultaneous-multi-slice-sms-epi-to-improve-functional-mri-of-the-subcortical-nuclei-of-the-basal-ganglia-at-ultra-high-field-7t
#13
Alexander M Puckett, Saskia Bollmann, Benedikt A Poser, Jake Palmer, Markus Barth, Ross Cunnington
The nuclei of the basal ganglia pose a special problem for functional MRI, especially at ultra-high field, because T2* variations between different regions result in suboptimal BOLD sensitivity when using gradient-echo echo-planar imaging (EPI). Specifically, the iron-rich lentiform nucleus of the basal ganglia, including the putamen and globus pallidus, suffers from substantial signal loss when imaging is performed using conventional single-echo EPI with echo times (TE) optimized for the cortex. Multi-echo EPI acquires several echoes at different echo times for every imaging slice, allowing images to be reconstructed with a weighting of echo times that is optimized individually for each voxel according to the underlying tissue or T2* properties...
December 2, 2017: NeuroImage
https://www.readbyqxmd.com/read/29197870/detection-of-acute-tubular-necrosis-using-blood-oxygenation-level-dependent-bold-mri
#14
Frederic Bauer, Jan Wald, Felix Jan Bauer, Lisa Maria Dahlkamp, Felix S Seibert, Nikolaos Pagonas, Egbert Gedat, Nina Babel, Walter Zidek, Christian von Bodman, Joachim Noldus, Dieter Liermann, Timm H Westhoff
BACKGROUND/AIMS: To date, there is no imaging technique to assess tubular function in vivo. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) measures tissue oxygenation based on the transverse relaxation rate (R2*). The present study investigates whether BOLD MRI can assess tubular function using a tubule-specific pharmacological maneuver. METHODS: Cross sectional study with 28 participants including 9 subjects with ATN-induced acute kidney injury (AKI), 9 healthy controls, and 10 subjects with nephron sparing tumor resection (NSS) with clamping of the renal artery serving as a model of ischemia/reperfusion (I/R)-induced subclinical ATN (median clamping time 15 min, no significant decrease of eGFR, p=0...
December 4, 2017: Kidney & Blood Pressure Research
https://www.readbyqxmd.com/read/29176647/mri-simulation-study-investigating-effects-of-vessel-topology-diffusion-and-susceptibility-on-transverse-relaxation-rates-using-a-cylinder-fork-model
#15
Mohammed Salman Shazeeb, Jayashree Kalpathy-Cramer, Bashar Issa
Brain vasculature is conventionally represented as straight cylinders when simulating blood oxygenation level dependent (BOLD) contrast effects in functional magnetic resonance imaging (fMRI). In reality, the vasculature is more complicated with branching and coiling especially in tumors. Diffusion and susceptibility changes can also introduce variations in the relaxation mechanisms within tumors. This study introduces a simple cylinder fork model (CFM) and investigates the effects of vessel topology, diffusion, and susceptibility on the transverse relaxation rates R2* and R2...
November 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29163072/altered-functional-brain-connectomes-between-sporadic-and-familial-parkinson-s-patients
#16
Yan Tang, Xue Xiao, Hua Xie, Chang-Min Wan, Li Meng, Zhen-Hua Liu, Wei-Hua Liao, Bei-Sha Tang, Ji-Feng Guo
Familial Parkinson's disease (PD) is often caused by mutation of a certain gene, while sporadic PD is associated with variants of genes which can influence the susceptibility to PD. The goal of this study was to investigate the difference between the two forms of PD in terms of brain abnormalities using resting-state functional MRI and graph theory. Thirty-one familial PD patients and 36 sporadic PD patients underwent resting-state functional MRI scanning. Frequency-dependent functional connectivity was calculated for each subject using wavelet-based correlations of BOLD signal over 246 brain regions from Brainnetome Atlas...
2017: Frontiers in Neuroanatomy
https://www.readbyqxmd.com/read/29160088/resting-state-functional-connectivity-of-the-subthalamic-nucleus-to-limbic-associative-and-motor-networks
#17
Sheeba Arnold Anteraper, Xavier Guell, Susan Whitfield-Gabrieli, Christina Triantafyllou, Aaron Mattfeld, John D Gabrieli, Maiya Geddes
The subthalamic nucleus (STN) is a small structure situated deep in the mid-brain that exhibits wide-ranging functionality. In addition to its role in motor control, the STN is considered a hub for synchronizing aspects of emotion and cognition including attention, inhibitory control, motivation, and working memory. Evidence from neuroanatomical tracer studies suggests that the medial, ventromedial, and dorsolateral parts of the STN correspond to limbic, associative, and motor subdivisions respectively. While the extent of STN functional anatomical overlap remains unclear, BOLD imaging of the STN may provide complementary information about the diverse functions of this structure...
November 21, 2017: Brain Connectivity
https://www.readbyqxmd.com/read/29159960/mapping-the-structural-and-functional-network-architecture-of-the-medial-temporal-lobe-using-7t-mri
#18
Preya Shah, Danielle S Bassett, Laura E M Wisse, John A Detre, Joel M Stein, Paul A Yushkevich, Russell T Shinohara, John B Pluta, Elijah Valenciano, Molly Daffner, David A Wolk, Mark A Elliott, Brian Litt, Kathryn A Davis, Sandhitsu R Das
Medial temporal lobe (MTL) subregions play integral roles in memory function and are differentially affected in various neurological and psychiatric disorders. The ability to structurally and functionally characterize these subregions may be important to understanding MTL physiology and diagnosing diseases involving the MTL. In this study, we characterized network architecture of the MTL in healthy subjects (n = 31) using both resting state functional MRI and MTL-focused T2-weighted structural MRI at 7 tesla...
November 20, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/29154684/brain-functional-connectivity-in-headache-disorders-a-narrative-review-of-mri-investigations
#19
Catherine D Chong, Todd J Schwedt, Anders Hougaard
Resting-state functional magnetic resonance imaging (rs-fMRI) is used to interrogate the functional connectivity and network organization amongst brain regions. Functional connectivity is determined by measuring the extent of synchronization in the spontaneous fluctuations of blood oxygenation level dependent (BOLD) signal. Here, we review current rs-fMRI studies in headache disorders including migraine, trigeminal autonomic cephalalgias, and medication overuse headache. We discuss (1) brain network alterations that are shared amongst the different headache disorders and (2) network abnormalities distinct to each headache disorder...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/29152994/decreased-connectivity-and-increased-bold-complexity-in-the-default-mode-network-in-individuals-with-chronic-fatigue-syndrome
#20
Zack Y Shan, Kevin Finegan, Sandeep Bhuta, Timothy Ireland, Donald R Staines, Sonya M Marshall-Gradisnik, Leighton R Barnden
The chronic fatigue syndrome / myalgic encephalomyelitis (CFS) is a debilitating disease with unknown pathophysiology and no diagnostic test. This study investigated the default mode network (DMN) in order to understand the pathophysiology of CFS and to identify potential biomarkers. Using functional MRI (fMRI) collected from 72 subjects (45 CFS and 27 controls) with a temporal resolution of 0.798s, we evaluated the default mode network using static functional connectivity (FC), dynamic functional connectivity (DFC) and DFC complexity, blood oxygenation level dependent (BOLD) activation maps and complexity of activity...
November 20, 2017: Brain Connectivity
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