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BOLD fMRI

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https://www.readbyqxmd.com/read/28101523/spatial-mnemonic-encoding-theta-power-decreases-and-medial-temporal-lobe-bold-increases-co-occur-during-the-usage-of-the-method-of-loci
#1
Marie-Christin Fellner, Gregor Volberg, Maria Wimber, Markus Goldhacker, Mark W Greenlee, Simon Hanslmayr
The method of loci is one, if not the most, efficient mnemonic encoding strategy. This spatial mnemonic combines the core cognitive processes commonly linked to medial temporal lobe (MTL) activity: spatial and associative memory processes. During such processes, fMRI studies consistently demonstrate MTL activity, while electrophysiological studies have emphasized the important role of theta oscillations (3-8 Hz) in the MTL. However, it is still unknown whether increases or decreases in theta power co-occur with increased BOLD signal in the MTL during memory encoding...
November 2016: ENeuro
https://www.readbyqxmd.com/read/28099241/fmri-with-central-vision-loss-effects-of-fixation-locus-and-stimulus-type
#2
Tina Plank, Jozef Frolo, Sabine Brandl-Rühle, Agnes B Renner, Herbert Jägle, Mark W Greenlee
PURPOSE: In patients with central visual field scotomata, a large part of visual cortex is not adequately stimulated. Patients often use a new eccentric fixation area on intact peripheral retina ("preferred retinal locus"-PRL) that functions as a pseudo-fovea. We used functional magnetic resonance imaging (fMRI) to examine whether stimulating this pseudo-fovea leads to increased activation or altered activation patterns in visual cortex in comparison to stimulating a comparable peripheral area in the opposite hemifield (OppPRL)...
January 18, 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28093359/fmri-characterisation-of-widespread-brain-networks-relevant-for-behavioural-variability-in-fine-hand-motor-control-with-and-without-visual-feedback
#3
Stephen D Mayhew, Camillo Porcaro, Franca Tecchio, Andrew P Bagshaw
A bilateral visuo-parietal-motor network is responsible for fine control of hand movements. However, the sub-regions which are devoted to maintenance of contraction stability and how these processes fluctuate with trial-quality of task execution and in the presence/absence of visual feedback remains unclear. We addressed this by integrating behavioural and fMRI measurements during right-hand isometric compression of a compliant rubber bulb, at 10% and 30% of maximum voluntary contraction, both with and without visual feedback of the applied force...
January 13, 2017: NeuroImage
https://www.readbyqxmd.com/read/28089677/global-signal-regression-acts-as-a-temporal-downweighting-process-in-resting-state-fmri
#4
Alican Nalci, Bhaskar D Rao, Thomas T Liu
In resting-state functional MRI (rsfMRI), the correlation between blood oxygenation level dependent (BOLD) signals across different brain regions is used to estimate the functional connectivity of the brain. This approach has led to the identification of a number of resting-state networks, including the default mode network (DMN) and the task positive network (TPN). Global signal regression (GSR) is a widely used pre-processing step in rsfMRI that has been shown to improve the spatial specificity of the estimated resting-state networks...
January 9, 2017: NeuroImage
https://www.readbyqxmd.com/read/28089656/how-do-antidepressants-influence-the-bold-signal-in-the-developing-brain
#5
REVIEW
Julia J Harris, Clare Reynell
Depression is a highly prevalent life-threatening disorder, with its first onset commonly occurring during adolescence. Adolescent depression is increasingly being treated with antidepressants, such as fluoxetine. The use of medication during this sensitive period of physiological and cognitive brain development produces neurobiological changes, some of which may outlast the course of treatment. In this review, we look at how antidepressant treatment in adolescence is likely to alter neurovascular coupling and brain energy use and how these changes, in turn, affect our ability to identify neuronal activity changes between participant groups...
December 21, 2016: Developmental Cognitive Neuroscience
https://www.readbyqxmd.com/read/28088483/physiology-recording-with-magnetic-field-probes-for-fmri-denoising
#6
Simon Gross, Laetitia Vionnet, Lars Kasper, Benjamin E Dietrich, Klaas P Pruessmann
Physiological noise originating in cardiovascular and respiratory processes is a substantial confound in BOLD fMRI. When unaccounted for it reduces the temporal SNR and causes error in inferred brain activity and connectivity. Physiology correction typically relies on auxiliary measurements with peripheral devices such as ECG, pulse oximeters, and breathing belts. These require direct skin contact or at least a tight fit, impairing subject comfort and adding to the setup time. In this work, we explore a touch-free alternative for physiology recording, using magnetic detection with NMR field probes...
January 11, 2017: NeuroImage
https://www.readbyqxmd.com/read/28079057/functional-mri-of-the-reserpine-induced-putative-rat-model-of-fibromyalgia-reveals-discriminatory-patterns-of-functional-augmentation-to-acute-nociceptive-stimuli
#7
Jack A Wells, Sayaka Shibata, Akihiko Fujikawa, Masayasu Takahashi, Tsuneo Saga, Ichio Aoki
Functional neuroimaging, applied to pre-clinical models of chronic pain, offers unique advantages in the drive to discover new treatments for this prevalent and oppressive condition. The high spatial and temporal resolution of fMRI affords detailed mapping of regional pharmacodynamics that underlie mechanisms of pain suppression by new analgesics. Despite evidence supporting the translational relevance of this approach, relatively few studies have investigated fMRI abnormalities in rodent models of chronic pain...
January 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28077303/analysis-and-correction-of-field-fluctuations-in-fmri-data-using-field-monitoring
#8
Saskia Bollmann, Lars Kasper, S Johanna Vannesjo, Andreea O Diaconescu, Benjamin E Dietrich, Simon Gross, Klaas E Stephan, Klaas P Pruessmann
This work investigates the role of magnetic field fluctuations as a confound in fMRI. In standard fMRI experiments with single-shot EPI acquisition the uniform and gradient components of the magnetic field were recorded with NMR field sensors. By principal component analysis it is found that differences of field evolution between the EPI readouts are explainable by few components relating to slow and within-shot field dynamics of hardware and physiological origin. The impact of fluctuating field components is studied by selective data correction and assessment of its influence on image fluctuation and SFNR...
January 8, 2017: NeuroImage
https://www.readbyqxmd.com/read/28076368/functional-laterality-of-task-evoked-activation-in-sensorimotor-cortex-of-preterm-infants-an-optimized-3-t-fmri-study-employing-a-customized-neonatal-head-coil
#9
Lukas Scheef, Jurek A Nordmeyer-Massner, Adam Pr Smith-Collins, Nicole Müller, Gaby Stegmann-Woessner, Jacob Jankowski, Jürgen Gieseke, Mark Born, Hermann Seitz, Peter Bartmann, Hans H Schild, Klaas P Pruessmann, Axel Heep, Henning Boecker
BACKGROUND: Functional magnetic resonance imaging (fMRI) in neonates has been introduced as a non-invasive method for studying sensorimotor processing in the developing brain. However, previous neonatal studies have delivered conflicting results regarding localization, lateralization, and directionality of blood oxygenation level dependent (BOLD) responses in sensorimotor cortex (SMC). Amongst the confounding factors in interpreting neonatal fMRI studies include the use of standard adult MR-coils providing insufficient signal to noise, and liberal statistical thresholds, compromising clinical interpretation at the single subject level...
2017: PloS One
https://www.readbyqxmd.com/read/28074492/confirmation-of-resting-state-bold-fluctuations-in-the-human-brainstem-and-spinal-cord-after-identification-and-removal-of-physiological-noise
#10
Shreyas Harita, Patrick W Stroman
PURPOSE: Resting-state functional MRI (rs-fMRI) has been used to investigate networks within the cortex, but its use in the brainstem (BS) and spinal cord (SC) has been limited. This region presents challenges for fMRI, partly because of sources of physiological noise. This study aims to quantify noise contributions to rs-fMRI, and to obtain evidence of resting-state blood oxygenation level-dependent (BOLD) fluctuations. METHODS: Resting-state-fMRI data were obtained from the BS/SC in 16 participants, at 3 Tesla, with T2 -weighted single-shot fast spin-echo imaging...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28063973/the-effect-of-acquisition-resolution-on-orientation-decoding-from-v1-bold-fmri-at-7-tesla
#11
Ayan Sengupta, Renat Yakupov, Oliver Speck, Stefan Pollmann, Michael Hanke
A decade after it was shown that the orientation of visual grating stimuli can be decoded from human visual cortex activity by means of multivariate pattern classification of BOLD fMRI data, numerous studies have investigated which aspects of neuronal activity are reflected in BOLD response patterns and are accessible for decoding. However, it remains inconclusive what the effect of acquisition resolution on BOLD fMRI decoding analyses is. The present study is the first to provide empirical ultra high-field fMRI data recorded at four spatial resolutions (0...
January 4, 2017: NeuroImage
https://www.readbyqxmd.com/read/28060861/predicting-the-multisensory-consequences-of-one-s-own-action-bold-suppression-in-auditory-and-visual-cortices
#12
Benjamin Straube, Bianca M van Kemenade, B Ezgi Arikan, Katja Fiehler, Dirk T Leube, Laurence R Harris, Tilo Kircher
Predictive mechanisms are essential to successfully interact with the environment and to compensate for delays in the transmission of neural signals. However, whether and how we predict multisensory action outcomes remains largely unknown. Here we investigated the existence of multisensory predictive mechanisms in a context where actions have outcomes in different modalities. During fMRI data acquisition auditory, visual and auditory-visual stimuli were presented in active and passive conditions. In the active condition, a self-initiated button press elicited the stimuli with variable short delays (0-417ms) between action and outcome, and participants had to detect the presence of a delay for auditory or visual outcome (task modality)...
2017: PloS One
https://www.readbyqxmd.com/read/28050345/functional-mri-vs-navigated-tms-to-optimize-m1-seed-volume-delineation-for-dti-tractography-a-prospective-study-in-patients-with-brain-tumours-adjacent-to-the-corticospinal-tract
#13
Carolin Weiss Lucas, Irada Tursunova, Volker Neuschmelting, Charlotte Nettekoven, Ana-Maria Oros-Peusquens, Gabriele Stoffels, Andrea Maria Faymonville, Shah N Jon, Karl Josef Langen, Hannah Lockau, Roland Goldbrunner, Christian Grefkes
BACKGROUND: DTI-based tractography is an increasingly important tool for planning brain surgery in patients suffering from brain tumours. However, there is an ongoing debate which tracking approaches yield the most valid results. Especially the use of functional localizer data such as navigated transcranial magnetic stimulation (nTMS) or functional magnetic resonance imaging (fMRI) seem to improve fibre tracking data in conditions where anatomical landmarks are less informative due to tumour-induced distortions of the gyral anatomy...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28048928/we-fg-206-02-brief-variations-of-bold-signal-in-resting-state-fmri-leading-to-functional-connectivity-pattern-identification
#14
N Ball, N Chen
PURPOSE: To assess the role of spontaneous brain activity in identifying functional connectivity patterns in the brain during resting-state using both high and low blood-oxygen level dependent (BOLD) signals from functional magnetic resonance imaging (fMRI). METHODS: fMRI BOLD signals within seed regions from known functional connectivity networks were extracted to find an average seed-region time profile. A threshold was applied to the BOLD signal and and time points were selected where the BOLD signal satisfied the threshold requirements...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047432/su-g-iep1-11-resting-state-fluctuation-of-bold-signal-amplitude-for-mapping-cerebrovascular-reactivity-in-presurgical-functional-mri
#15
P Wang, P Hou, S Kesler, R Colen, A Kumar, S Prabhu, H Liu
PURPOSE: Cerebrovascular reactivity (CVR) MRI with hypercapnia challenges, such as a breath-hold (BH) task, has been proposed to indicate areas with neurovascular uncoupling potentials for presurgical functional MRI (fMRI). This study aimed to explore the use of resting-state (RS) fMRI, in particular, the RS fluctuation of amplitude (RSFA) for detecting the impaired CVR and compare with BH MRI in patients with gliomas. METHODS: The BH and RS fMRI from six patients as part of their presurgical fMRI studies were analyzed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28045051/randomized-trial-on-the-effects-of-a-combined-physical-cognitive-training-in-aged-mci-subjects-the-train-the-brain-study
#16
(no author information available yet)
Age-related cognitive impairment and dementia are an increasing societal burden. Epidemiological studies indicate that lifestyle factors, e.g. physical, cognitive and social activities, correlate with reduced dementia risk; moreover, positive effects on cognition of physical/cognitive training have been found in cognitively unimpaired elders. Less is known about effectiveness and action mechanisms of physical/cognitive training in elders already suffering from Mild Cognitive Impairment (MCI), a population at high risk for dementia...
January 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28041979/a-three-dimensional-single-scan-approach-for-the-measurement-of-changes-in-cerebral-blood-volume-blood-flow-and-blood-oxygenation-weighted-signals-during-functional-stimulation
#17
Ying Cheng, Qin Qin, Peter C M van Zijl, James J Pekar, Jun Hua
The blood-oxygenation-level-dependent (BOLD) effect reflects ensemble changes in several physiological parameters such as cerebral blood volume (CBV), blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2). Quantitative BOLD approaches have been developed to estimate CMRO2 dynamics from BOLD, CBF and CBV responses, generally using separate scans. The ability to detect changes in these parameters in a single scan would shorten the total scan time and reduce temporal variations in physiology or neuronal responses...
December 29, 2016: NeuroImage
https://www.readbyqxmd.com/read/28031993/support-vector-machine-classification-of-arterial-volume-weighted-arterial-spin-tagging-images
#18
Yash S Shah, Luis Hernandez-Garcia, Hesamoddin Jahanian, Scott J Peltier
INTRODUCTION: In recent years, machine-learning techniques have gained growing popularity in medical image analysis. Temporal brain-state classification is one of the major applications of machine-learning techniques in functional magnetic resonance imaging (fMRI) brain data. This article explores the use of support vector machine (SVM) classification technique with motor-visual activation paradigm to perform brain-state classification into activation and rest with an emphasis on different acquisition techniques...
December 2016: Brain and Behavior
https://www.readbyqxmd.com/read/28027960/investigating-resting-state-functional-connectivity-in-the-cervical-spinal-cord-at-3t
#19
Falk Eippert, Yazhuo Kong, Anderson M Winkler, Jesper L Andersson, Jürgen Finsterbusch, Christian Büchel, Jonathan C W Brooks, Irene Tracey
The study of spontaneous fluctuations in the blood-oxygen-level-dependent (BOLD) signal has recently been extended from the brain to the spinal cord. Two ultra-high field functional magnetic resonance imaging (fMRI) studies in humans have provided evidence for reproducible resting-state connectivity between the dorsal horns as well as between the ventral horns, and a study in non-human primates has shown that these resting-state signals are impacted by spinal cord injury. As these studies were carried out at ultra-high field strengths using region-of-interest (ROI) based analyses, we investigated whether such resting-state signals could also be observed at the clinically more prevalent field strength of 3T...
December 24, 2016: NeuroImage
https://www.readbyqxmd.com/read/28018165/investigating-the-group-level-impact-of-advanced-dual-echo-fmri-combinations
#20
Ádám Kettinger, Christopher Hill, Zoltán Vidnyánszky, Christian Windischberger, Zoltán Nagy
Multi-echo fMRI data acquisition has been widely investigated and suggested to optimize sensitivity for detecting the BOLD signal. Several methods have also been proposed for the combination of data with different echo times. The aim of the present study was to investigate whether these advanced echo combination methods provide advantages over the simple averaging of echoes when state-of-the-art group-level random-effect analyses are performed. Both resting-state and task-based dual-echo fMRI data were collected from 27 healthy adult individuals (14 male, mean age = 25...
2016: Frontiers in Neuroscience
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