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BOLD fMRI

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https://www.readbyqxmd.com/read/28928708/neural-patterns-of-reorganization-after-intensive-robot-assisted-virtual-reality-therapy-and-repetitive-task-practice-in-patients-with-chronic-stroke
#1
Soha Saleh, Gerard Fluet, Qinyin Qiu, Alma Merians, Sergei V Adamovich, Eugene Tunik
Several approaches to rehabilitation of the hand following a stroke have emerged over the last two decades. These treatments, including repetitive task practice (RTP), robotically assisted rehabilitation and virtual rehabilitation activities, produce improvements in hand function but have yet to reinstate function to pre-stroke levels-which likely depends on developing the therapies to impact cortical reorganization in a manner that favors or supports recovery. Understanding cortical reorganization that underlies the above interventions is therefore critical to inform how such therapies can be utilized and improved and is the focus of the current investigation...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28923276/rapid-whole-brain-resting-state-fmri-at-3%C3%A2-tesla-efficiency-optimized-three-dimensional-epi-versus-repetition-time-matched-simultaneous-multi-slice-epi
#2
Rüdiger Stirnberg, Willem Huijbers, Daniel Brenner, Benedikt A Poser, Monique Breteler, Tony Stöcker
State-of-the-art simultaneous-multi-slice (SMS-)EPI and 3D-EPI share several properties that benefit functional MRI acquisition. Both sequences employ equivalent parallel imaging undersampling with controlled aliasing to achieve high temporal sampling rates. As a volumetric imaging sequence, 3D-EPI offers additional means of acceleration complementary to 2D-CAIPIRINHA sampling, such as fast water excitation and elliptical sampling. We performed an application-oriented comparison between a tailored, six-fold CAIPIRINHA-accelerated 3D-EPI protocol at 530 ms temporal and 2...
September 15, 2017: NeuroImage
https://www.readbyqxmd.com/read/28922510/effects-of-spatial-smoothing-on-functional-brain-networks
#3
Tuomas Alakörkkö, Heini Saarimäki, Enrico Glerean, Jari Saramäki, Onerva Korhonen
Graph-theoretical methods have rapidly become a standard tool in studies of the structure and function of the human brain. Whereas the structural connectome can be fairly straightforwardly mapped onto a complex network, there are more degrees of freedom in constructing networks that represent functional connections between brain areas. For fMRI data, such networks are typically built by aggregating the BOLD signal time series of voxels into larger entities (such as Regions of Interest in some brain atlas), and determining their connection strengths from some measure of time-series correlations...
September 18, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28917813/structural-impacts-on-the-timing-and-amplitude-of-the-negative-bold-response
#4
David Provencher, Alexandre Bizeau, Guillaume Gilbert, Yves Bérubé-Lauzière, Kevin Whittingstall
The positive (PBR) and negative BOLD responses (NBR) arising in task-fMRI display varying magnitudes and dynamics across voxels. While the effects of structure, particularly of veins, on the PBR have been studied, little is known of NBR-structure relationships. Like the PBR, the NBR is often used as a surrogate marker of neuronal activation in both basic and clinical research and assessing its relationship with cortical structure may help interpret group differences. We therefore investigated how local structure affects BOLD amplitude and timing in PBR and NBR areas using multi-band fMRI during visual stimulation to obtain high temporal resolution (TR=0...
September 13, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28915853/low-threshold-unmyelinated-mechanoafferents-can-modulate-pain
#5
Kathrin Habig, Anne Schänzer, Wolfgang Schirner, Gothje Lautenschläger, Benjamin Dassinger, Håkan Olausson, Frank Birklein, Elke R Gizewski, Heidrun H Krämer
BACKGROUND: Human, hairy skin contains a subgroup of C-fibers, the C-low threshold mechanoreceptive afferents ((C-LTMR) C-tactile or C-touch (CT) fibers) that are linked with the signaling of affective aspects of human touch. Recent studies suggest an involvement of these afferents in the modulation of pain in healthy volunteers. Small fiber neuropathy (SFN) is associated with a damage of C-fibers. Therefore, an impairment of C-LTMRs can be assumed. We aimed to elaborate a possible role of CT-afferents in pain modulation by investigating healthy volunteers and SFN-patients...
September 15, 2017: BMC Neurology
https://www.readbyqxmd.com/read/28914607/cortex-wide-bold-fmri-activity-reflects-locally-recorded-slow-oscillation-associated-calcium-waves
#6
Miriam Schwalm, Florian Schmid, Lydia Wachsmuth, Hendrik Backhaus, Andrea Kronfeld, Felipe Aedo Jury, Pierre-Hugues Prouvot, Consuelo Fois, Franziska Albers, Timo van Alst, Cornelius Faber, Albrecht Stroh
Spontaneous slow oscillation-associated slow wave activity represents an internally generated state which is characterized by alternations of network quiescence and stereotypical episodes of neuronal activity - slow wave events. However, it remains unclear which macroscopic signal is related to these active periods of the slow wave rhythm. We used optic fiber-based calcium recordings of local neural populations in cortex and thalamus to detect neurophysiologically defined slow calcium waves in isoflurane anesthetized rats...
September 15, 2017: ELife
https://www.readbyqxmd.com/read/28913727/sleep-amount-differentially-affects-fear-processing-neural-circuitry-in-pediatric-anxiety-a-preliminary-fmri-investigation
#7
Christina O Carlisi, Kevin Hilbert, Amanda E Guyer, Monique Ernst
Insufficient sleep, as well as the incidence of anxiety disorders, both peak during adolescence. While both conditions present perturbations in fear-processing-related neurocircuitry, it is unknown whether these neurofunctional alterations directly link anxiety and compromised sleep in adolescents. Fourteen anxious adolescents (AAs) and 19 healthy adolescents (HAs) were compared on a measure of sleep amount and neural responses to negatively valenced faces during fMRI. Group differences in neural response to negative faces emerged in the dorsal anterior cingulate cortex (dACC) and the hippocampus...
September 14, 2017: Cognitive, Affective & Behavioral Neuroscience
https://www.readbyqxmd.com/read/28913163/general-and-selective-brain-connectivity-alterations-in-essential-tremor-a-resting-state-fmri-study
#8
Karsten Mueller, Robert Jech, Martina Hoskovcová, Olga Ulmanová, Dušan Urgošík, Josef Vymazal, Evžen Růžička
Although essential tremor is the most common movement disorder, there is little knowledge about the pathophysiological mechanisms of this disease. Therefore, we explored brain connectivity based on slow spontaneous fluctuations of blood oxygenation level dependent (BOLD) signal in patients with essential tremor (ET). A cohort of 19 ET patients and 23 healthy individuals were scanned in resting condition using functional magnetic resonance imaging (fMRI). General connectivity was assessed by eigenvector centrality (EC) mapping...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28912749/functional-connectivity-of-the-corpus-callosum-in-epilepsy-patients-with-secondarily-generalized-seizures
#9
Syu-Jyun Peng, Yue-Loong Hsin
The corpus callosum (CC) plays an important role in generalization of seizure activity. We used resting-state function magnetic resonance imaging (rs-fMRI) to investigate the regional and interregional functional connectivity of CC in patients with magnetic resonance imaging (MRI)-negative and secondarily generalized seizures. We measured the multi-regional coherences of blood oxygen level-dependent (BOLD) signals via rs-fMRI, cortical thickness via high-resolution T1-weighted MRI, and white matter (WM) integrity via diffusion-tensor imaging in 16 epilepsy patients as well as in 16 age- and gender-matched healthy subjects...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28893378/localization-of-spontaneous-bursting-neuronal-activity-in-the-preterm-human-brain-with-simultaneous-eeg-fmri
#10
Tomoki Arichi, Kimberley Whitehead, Giovanni Barone, Ronit Pressler, Francesco Padormo, A David Edwards, Lorenzo Fabrizi
Electroencephalographic recordings from the developing human brain are characterized by spontaneous neuronal bursts, the most common of which is the delta brush. Although similar events in animal models are known to occur in areas of immature cortex and drive their development, their origin in humans has not yet been identified. Here, we use simultaneous EEG-fMRI to localise the source of delta brush events in 10 preterm infants aged 32-36 postmenstrual weeks. The most frequent patterns were left and right posterior-temporal delta brushes which were associated in the left hemisphere with ipsilateral BOLD activation in the insula only; and in the right hemisphere in both the insular and temporal cortices...
September 12, 2017: ELife
https://www.readbyqxmd.com/read/28890417/the-impact-of-vessel-size-orientation-and-intravascular-contribution-on-the-neurovascular-fingerprint-of-bold-bssfp-fmri
#11
Mario Gilberto Báez-Yánez, Philipp Ehses, Christian Mirkes, Philbert S Tsai, David Kleinfeld, Klaus Scheffler
Monte Carlo simulations have been used to analyze oxygenation-related signal changes in pass-band balanced steady state free precession (bSSFP) as well as in gradient echo (GE) and spin echo (SE) sequences. Signal changes were calculated for artificial cylinders and neurovascular networks acquired from the mouse parietal cortex by two-photon laser scanning microscopy at 1 μm isotropic resolution. Signal changes as a function of vessel size, blood volume, vessel orientation to the main magnetic field B0 as well as relations of intra- and extravascular and of micro- and macrovascular contributions have been analyzed...
September 8, 2017: NeuroImage
https://www.readbyqxmd.com/read/28890416/bayesian-population-receptive-field-modelling
#12
REVIEW
Peter Zeidman, Edward Harry Silson, Dietrich Samuel Schwarzkopf, Chris Ian Baker, Will Penny
We introduce a probabilistic (Bayesian) framework and associated software toolbox for mapping population receptive fields (pRFs) based on fMRI data. This generic approach is intended to work with stimuli of any dimension and is demonstrated and validated in the context of 2D retinotopic mapping. The framework enables the experimenter to specify generative (encoding) models of fMRI timeseries, in which experimental stimuli enter a pRF model of neural activity, which in turns drives a nonlinear model of neurovascular coupling and Blood Oxygenation Level Dependent (BOLD) response...
September 8, 2017: NeuroImage
https://www.readbyqxmd.com/read/28885752/dual-echo-asl-contributes-to-decrypting-the-link-between-functional-connectivity-and-cerebral-blow-flow
#13
Silvia F Storti, Ilaria Boscolo Galazzo, Stefania Montemezzi, Gloria Menegaz, Francesca B Pizzini
Arterial spin labeling (ASL) MRI with a dual-echo readout module (DE-ASL) enables noninvasive simultaneous acquisition of cerebral blood flow (CBF)-weighted images and blood oxygenation level dependent (BOLD) contrast. Up to date, resting-state functional connectivity (FC) studies based on CBF fluctuations have been very limited, while the BOLD is still the method most frequently used. The purposes of this technical report were (i) to assess the potentiality of the DE-ASL sequence for the quantification of resting-state FC and brain organization, with respect to the conventional BOLD (cvBOLD) and (ii) to investigate the relationship between a series of complex network measures and the CBF information...
September 8, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28884708/dual-echo-asl-based-assessment-of-motor-networks-a-feasibility-study
#14
Silvia Francesca Storti, Ilaria Boscolo Galazzo, Francesca B Pizzini, Gloria Menegaz
OBJECTIVE: Dual-echo arterial spin labeling (DE-ASL) techniques have been recently proposed for the simultaneous acquisition of ASL and blood-oxygenation-level-dependent (BOLD)-functional magnetic resonance imaging (fMRI) data. The assessment of this technique in detecting functional connectivity at rest or during motor and motor imagery tasks is still unexplored both per-se and in comparison with conventional methods. The purpose is to quantify the sensitivity of the DE-ASL sequence with respect to the conventional fMRI sequence (cvBOLD) in detecting brain activations, and to assess and compare the relevance of node features in decoding the network structure...
September 8, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28882632/spatial-specificity-of-the-functional-mri-blood-oxygenation-response-relative-to-neuronal-activity
#15
Denis Chaimow, Essa Yacoub, Kâmil Uğurbil, Amir Shmuel
Previous attempts at characterizing the spatial specificity of the blood oxygenation level dependent functional MRI (BOLD fMRI) response by estimating its point-spread function (PSF) have conventionally relied on spatial representations of visual stimuli in area V1. Consequently, their estimates were confounded by the width and scatter of receptive fields of V1 neurons. Here, we circumvent these limits by instead using the inherent cortical spatial organization of ocular dominance columns (ODCs) to determine the PSF for both Gradient Echo (GE) and Spin Echo (SE) BOLD imaging at 7 T...
September 4, 2017: NeuroImage
https://www.readbyqxmd.com/read/28881021/convergence-of-fmri-and-erp-measures-of-emotional-face-processing-in-combat-exposed-u-s-military-veterans
#16
Annmarie MacNamara, Christine A Rabinak, Amy E Kennedy, K Luan Phan
The late positive potential (LPP) and fMRI blood-oxygen-level dependent (BOLD) activity can provide complementary measures of the processing of affective and social stimuli. Separate lines of research using these measures have often employed the same stimuli, paradigms, and samples; however, there remains relatively little understanding of the way in which individual differences in one of these measures relates to the other, and all prior research has been conducted in psychiatrically healthy samples and using emotional scenes (not faces)...
September 7, 2017: Psychophysiology
https://www.readbyqxmd.com/read/28871034/domain-general-brain-regions-do-not-track-linguistic-input-as-closely-as-language-selective-regions
#17
Idan Blank, Evelina Fedorenko
Language comprehension engages a cortical network of left frontal and temporal regions. Activity in this network is language-selective, showing virtually no modulation by non-linguistic tasks. In addition, language comprehension engages a second network consisting of bilateral frontal, parietal, cingulate, and insular regions. Activity in this "Multiple Demand (MD)" network scales with comprehension difficulty, but also with cognitive effort across a wide range of non-linguistic tasks in a domain-general fashion...
September 4, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28868791/predicting-hemispheric-dominance-for-language-production-in-healthy-individuals-using-support-vector-machine
#18
Laure Zago, Pierre-Yves Hervé, Robin Genuer, Alexandre Laurent, Bernard Mazoyer, Nathalie Tzourio-Mazoyer, Marc Joliot
We used a Support Vector Machine (SVM) classifier to assess hemispheric pattern of language dominance of 47 individuals categorized as non-typical for language from their hemispheric functional laterality index (HFLI) measured on a sentence minus word-list production fMRI-BOLD contrast map. The SVM classifier was trained at discriminating between Dominant and Non-Dominant hemispheric language production activation pattern on a group of 250 participants previously identified as Typicals (HFLI strongly leftward)...
September 3, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28867998/functional-magnetic-resonance-imaging-and-functional-near-infrared-spectroscopy-insights-from-combined-recording-studies
#19
REVIEW
Vanessa Scarapicchia, Cassandra Brown, Chantel Mayo, Jodie R Gawryluk
Although blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) is a widely available, non-invasive technique that offers excellent spatial resolution, it remains limited by practical constraints imposed by the scanner environment. More recently, functional near infrared spectroscopy (fNIRS) has emerged as an alternative hemodynamic-based approach that possesses a number of strengths where fMRI is limited, most notably in portability and higher tolerance for motion. To date, fNIRS has shown promise in its ability to shed light on the functioning of the human brain in populations and contexts previously inaccessible to fMRI...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28867941/affective-neuroimaging-in-generalized-anxiety-disorder-an-integrated-review
#20
Gregory A Fonzo, Amit Etkin
Affective neuroimaging has contributed to our knowledge of generalized anxiety disorder (GAD) through measurement of blood oxygenation level-dependent (BOLD) responses, which facilitate inference on neural responses to emotional stimuli during task-based functional magnetic resonance imaging (fMRI). In this article, the authors provide an integrated review of the task-based affective fMRI literature in GAD. Studies provide evidence for variable presence and directionality of BOLD abnormalities in limbic and prefrontal regions during reactivity to, regulation of, and learning from emotional cues...
June 2017: Dialogues in Clinical Neuroscience
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