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https://www.readbyqxmd.com/read/28336425/characterizing-object-and-position-dependent-response-profiles-to-uni-and-bilateral-stimulus-configurations-in-human-higher-visual-cortex-a-7t-fmri-study
#1
Joel Reithler, Judith C Peters, Rainer Goebel
Visual scenes are initially processed via segregated neural pathways dedicated to either of the two visual hemifields. Although higher-order visual areas are generally believed to utilize invariant object representations (abstracted away from features such as stimulus position), recent findings suggest they retain more spatial information than previously thought. Here, we assessed the nature of such higher-order object representations in human cortex using high-resolution fMRI at 7T, supported by corroborative 3T data...
March 21, 2017: NeuroImage
https://www.readbyqxmd.com/read/28336427/high-resolution-anatomical-and-quantitative-mri-of-the-entire-human-occipital-lobe-ex-vivo-at-9-4t
#2
S Sengupta, F J Fritz, R L Harms, S Hildebrand, D H Y Tse, B A Poser, R Goebel, A Roebroeck
Several magnetic resonance imaging (MRI) contrasts are sensitive to myelin content in gray matter in vivo which has ignited ambitions of MRI-based in vivo cortical histology. Ultra-high field (UHF) MRI, at fields of 7T and beyond, is crucial to provide the resolution and contrast needed to sample contrasts over the depth of the cortex and get closer to layer resolved imaging. Ex vivo MRI of human post mortem samples is an important stepping stone to investigate MRI contrast in the cortex, validate it against histology techniques applied in situ to the same tissue, and investigate the resolutions needed to translate ex vivo findings to in vivo UHF MRI...
March 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28336426/sar-simulations-safety
#3
Thomas M Fiedler, Mark E Ladd, Andreas K Bitz
At ultra-high fields, the assessment of radiofrequency (RF) safety presents several new challenges compared to low-field systems. Multi-channel RF transmit coils in combination with parallel transmit techniques produce time-dependent and spatially varying power loss densities in the tissue. Further, in ultra-high-field systems, localized field effects can be more pronounced due to a transition from the quasistationary to the electromagnetic field regime. Consequently, local information on the RF field is required for reliable RF safety assessment as well as for monitoring of RF exposure during MR examinations...
March 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323166/neural-foundations-of-overt-and-covert-actions
#4
Panagiotis G Simos, Eleftherios Kavroulakis, Thomas Maris, Efrosini Papadaki, Themistoklis Boursianis, Giorgos Kalaitzakis, Helen E Savaki
We used fMRI to assess the human brain areas activated for execution, observation and 1(st) person motor imagery of a visually guided tracing task with the index finger. Voxel-level conjunction analysis revealed several cortical areas activated in common across all three motor conditions, namely, the upper limb representation of the primary motor and somatosensory cortices, the dorsal and ventral premotor, the superior and inferior parietal cortices as well as the posterior part of the superior and middle temporal gyrus including the temporo-parietal junction (TPj) and the extrastriate body area (EBA)...
March 18, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323164/mapping-the-pharmacological-modulation-of-brain-oxygen-metabolism-the-effects-of-caffeine-on-absolute-cmro2-measured-using-dual-calibrated-fmri
#5
Alberto Merola, Michael A Germuska, Esther Ah Warnert, Lewys Richmond, Daniel Helme, Sharmila Khot, Kevin Murphy, Peter J Rogers, Judith E Hall, Richard G Wise
This study aims to map the acute effects of caffeine ingestion on grey matter oxygen metabolism and haemodynamics with a novel MRI method. Sixteen healthy caffeine consumers (8 males, age = 24.7±5.1) were recruited to this randomised, double-blind, placebo-controlled study. Each participant was scanned on two days before and after the delivery of an oral caffeine (250mg) or placebo capsule. Our measurements were obtained with a newly proposed estimation approach applied to data from a dual calibration fMRI experiment that uses hypercapnia and hyperoxia to modulate brain blood flow and oxygenation...
March 17, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323161/seeg-dipole-source-localization-based-on-an-empirical-bayesian-approach-taking-into-account-forward-model-uncertainties
#6
S Le Cam, R Ranta, V Caune, G Korats, L Koessler, L Maillard, V Louis-Dorr
Electromagnetic brain source localization consists in the inversion of a forward model based on a limited number of potential measurements. A wide range of methods has been developed to regularize this severely ill-posed problem and to reduce the solution space, imposing spatial smoothness, anatomical constraint or sparsity of the activated source map. This last criteria, based on physiological assumptions stating that in some particular events (e.g., epileptic spikes, evoked potential) few focal area of the brain are simultaneously actives, has gained more and more interest...
March 17, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323165/on-the-importance-of-modeling-fmri-transients-when-estimating-effective-connectivity-a-dynamic-causal-modeling-study-using-asl-data
#7
Martin Havlicek, Alard Roebroeck, Karl J Friston, Anna Gardumi, Dimo Ivanov, Kamil Uludag
Effective connectivity is commonly assessed using blood oxygenation level-dependent (BOLD) signals. In (Havlicek et al., 2015), we presented a novel, physiologically informed dynamic causal model (P-DCM) that extends current generative models. We demonstrated the improvements afforded by P-DCM in terms of the ability to model commonly observed neuronal and vascular transients in single regions. Here, we assess the ability of the novel and previous DCM variants to estimate effective connectivity among a network of five ROIs driven by a visuo-motor task...
March 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323163/cerebrospinal-and-interstitial-fluid-transport-via-the-glymphatic-pathway-modeled-by-optimal-mass-transport
#8
Vadim Ratner, Yi Gao, Hedok Lee, Rena Elkin, Maiken Nedergaard, Helene Benveniste, Allen Tannenbaum
The glymphatic pathway is a system which facilitates continuous cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange and plays a key role in removing waste products from the rodent brain. Dysfunction of the glymphatic pathway may be implicated in the pathophysiology of Alzheimer's disease. Intriguingly, the glymphatic system is most active during deep wave sleep general anesthesia. By using paramagnetic tracers administered into CSF of rodents, we previously showed the utility of MRI in characterizing a macroscopic whole brain view of glymphatic transport but we have yet to define and visualize the specific flow patterns...
March 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323162/an-asymmetrical-relationship-between-verbal-and-visual-thinking-converging-evidence-from-behavior-and-fmri
#9
Elinor Amit, Caitlyn Hoeflin, Nada Hamzah, Evelina Fedorenko
Humans rely on at least two modes of thought: verbal (inner speech) and visual (imagery). Are these modes independent, or does engaging in one entail engaging in the other? To address this question, we performed a behavioral and an fMRI study. In the behavioral experiment, participants received a prompt and were asked to either silently generate a sentence or create a visual image in their mind. They were then asked to judge the vividness of the resulting representation, and of the potentially accompanying representation in the other format...
March 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323160/effect-of-age-and-the-apoe-gene-on-metabolite-concentrations-in-the-posterior-cingulate-cortex
#10
Sana Suri, Uzay Emir, Charlotte J Stagg, Jamie Near, Ralf Mekle, Florian Schubert, E Zsoldos, Abda Mahmood, Archana Singh-Manoux, Mika Kivimäki, Klaus P Ebmeier, Clare E Mackay, Nicola Filippini
Proton magnetic resonance spectroscopy ((1)H-MRS) has provided valuable information about the neurochemical profile of Alzheimer's disease (AD). However, its clinical utility has been limited in part by the lack of consistent information on how metabolite concentrations vary in the normal aging brain and in carriers of apolipoprotein E (APOE) ε4, an established risk gene for AD. We quantified metabolites within an 8cm(3) voxel within the posterior cingulate cortex (PCC)/precuneus in 30 younger (20-40 years) and 151 cognitively healthy older individuals (60-85 years)...
March 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/28323159/functional-changes-in-the-reward-circuit-in-response-to-gaming-related-cues-after-training-with-a-commercial-video-game
#11
Tobias Gleich, Robert C Lorenz, Jürgen Gallinat, Simone Kühn
In the present longitudinal study, we aimed to investigate video game training associated neuronal changes in reward processing using functional magnetic resonance imaging (fMRI). We recruited 48 healthy young participants which were assigned to one of 2 groups: A group in which participants were instructed to play a commercial video game ("Super Mario 64 DS") on a portable Nintendo DS handheld console at least 30minutes a day over a period of two months (video gaming group; VG) or to a matched passive control group (CG)...
March 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/28315741/individual-classification-of-alzheimer-s-disease-with-diffusion-magnetic-resonance-imaging
#12
Tijn M Schouten, Marisa Koini, Frank de Vos, Stephan Seiler, Mark de Rooij, Anita Lechner, Reinhold Schmidt, Martijn van den Heuvel, Jeroen van der Grond, Serge A R B Rombouts
Diffusion magnetic resonance imaging (MRI) is a powerful non-invasive method to study white matter integrity, and is sensitive to detect differences in Alzheimer's disease (AD) patients. Diffusion MRI may be able to contribute towards reliable diagnosis of AD. We used diffusion MRI to classify AD patients (N=77), and controls (N=173). We use different methods to extract information from the diffusion MRI data. First, we use the voxel-wise diffusion tensor measures that have been skeletonised using tract based spatial statistics...
March 15, 2017: NeuroImage
https://www.readbyqxmd.com/read/28315740/population-based-mri-and-dti-templates-of-the-adult-ferret-brain-and-tools-for-voxelwise-analysis
#13
E B Hutchinson, S C Schwerin, K L Radomski, N Sadeghi, J Jenkins, M E Komlosh, M O Irfanoglu, S L Juliano, C Pierpaoli
Non-invasive imaging has the potential to play a crucial role in the characterization and translation of experimental animal models to investigate human brain development and disorders, especially when employed to study animal models that more accurately represent features of human neuroanatomy. The purpose of this study was to build and make available MRI and DTI templates and analysis tools for the ferret brain as the ferret is a well-suited species for pre-clinical MRI studies with folded cortical surface, relatively high white matter volume and body dimensions that allow imaging with pre-clinical MRI scanners...
March 15, 2017: NeuroImage
https://www.readbyqxmd.com/read/28315461/single-or-multi-frequency-generators-in-on-going-brain-activity-a-mechanistic-whole-brain-model-of-empirical-meg-data
#14
Gustavo Deco, Joana Cabral, Mark W Woolrich, Angus B A Stevner, Tim J van Hartevelt, Morten L Kringelbach
During rest, envelopes of band-limited on-going MEG signals co-vary across the brain in consistent patterns, which have been related to resting-state networks measured with fMRI. To investigate the genesis of such envelope correlations, we consider a whole-brain network model assuming two distinct fundamental scenarios: one where each brain area generates oscillations in a single frequency, and a novel one where each brain area can generate oscillations in multiple frequency bands. The models share, as a common generator of damped oscillations, the normal form of a supercritical Hopf bifurcation operating at the critical border between the steady state and the oscillatory regime...
March 14, 2017: NeuroImage
https://www.readbyqxmd.com/read/28315460/classification-and-characterization-of-periventricular-and-deep-white-matter-hyperintensities-on-mri-a-study-in-older-adults
#15
REVIEW
Ludovica Griffanti, Mark Jenkinson, Sana Suri, X X, Abda Mahmood, Nicola Filippini, Claire E Sexton, Anya Topiwala, Charlotte Allan, Mika Kivimäki, Archana Singh-Manoux, Klaus P Ebmeier, Clare E Mackay, Giovanna Zamboni
White matter hyperintensities (WMH) are frequently divided into periventricular (PWMH) and deep (DWMH), and the two classes have been associated with different cognitive, microstructural, and clinical correlates. However, although this distinction is widely used in visual ratings scales, how to best anatomically define the two classes is still disputed. In fact, the methods used to define PWMH and DWMH vary significantly between studies, making results difficult to compare. The purpose of this study was twofold: first, to compare four current criteria used to define PWMH and DWMH in a cohort of healthy older adults (mean age: 69...
March 14, 2017: NeuroImage
https://www.readbyqxmd.com/read/28315459/dynamic-reorganization-of-intrinsic-functional-networks-in-the-mouse-brain
#16
Joanes Grandjean, Maria Giulia Preti, Thomas Aw Bolton, Michaela Buerge, Erich Seifritz, Christopher R Pryce, Dimitri Van De Ville, Markus Rudin
Functional connectivity (FC) derived from resting-state functional magnetic resonance imaging (rs-fMRI) allows for the integrative study of neuronal processes at a macroscopic level. The majority of studies to date have assumed stationary interactions between brain regions, without considering the dynamic aspects of network organization. Only recently has the latter received increased attention, predominantly in human studies. Applying dynamic FC (dFC) analysis to mice is attractive given the relative simplicity of the mouse brain and the possibility to explore mechanisms underlying network dynamics using pharmacological, environmental or genetic interventions...
March 14, 2017: NeuroImage
https://www.readbyqxmd.com/read/28302591/benchmarking-of-participant-level-confound-regression-strategies-for-the-control-of-motion-artifact-in-studies-of-functional-connectivity
#17
Rastko Ciric, Daniel H Wolf, Jonathan D Power, David R Roalf, Graham Baum, Kosha Ruparel, Russell T Shinohara, Mark A Elliott, Simon B Eickhoff, Christos Davatzikos, Ruben C Gur, Raquel E Gur, Danielle S Bassett, Theodore D Satterthwaite
Since initial reports regarding the impact of motion artifact on measures of functional connectivity, there has been a proliferation of participant-level confound regression methods to limit its impact. However, many of the most commonly used techniques have not been systematically evaluated using a broad range of outcome measures. Here, we provide a systematic evaluation of 14 participant-level confound regression methods in 393 young adults. Specifically, we compare methods according to four benchmarks, including the residual relationship between motion and connectivity, distance-dependent effects of motion on connectivity, network identifiability, and additional degrees of freedom lost in confound regression...
March 13, 2017: NeuroImage
https://www.readbyqxmd.com/read/28300640/consistency-of-eeg-source-localization-and-connectivity-estimates
#18
Keyvan Mahjoory, Vadim V Nikulin, Loïc Botrel, Klaus Linkenkaer-Hansen, Marco M Fato, Stefan Haufe
As the EEG inverse problem does not have a unique solution, the sources reconstructed from EEG and their connectivity properties depend on forward and inverse modeling parameters such as the choice of an anatomical template and electrical model, prior assumptions on the sources, and further implementational details. In order to use source connectivity analysis as a reliable research tool, there is a need for stability across a wider range of standard estimation routines. Using resting state EEG recordings of N=65 participants acquired within two studies, we present the first comprehensive assessment of the consistency of EEG source localization and functional/effective connectivity metrics across two anatomical templates (ICBM152 and Colin27), three electrical models (BEM, FEM and spherical harmonics expansions), three inverse methods (WMNE, eLORETA and LCMV), and three software implementations (Brainstorm, Fieldtrip and our own toolbox)...
March 12, 2017: NeuroImage
https://www.readbyqxmd.com/read/28300639/sliding-window-analysis-tracks-fluctuations-in-amygdala-functional-connectivity-associated-with-physiological-arousal-and-vigilance-during-fear-conditioning
#19
Blazej M Baczkowski, Tom Johnstone, Henrik Walter, Susanne Erk, Ilya M Veer
We evaluated whether sliding-window analysis can reveal functionally relevant brain network dynamics during a well-established fear conditioning paradigm. To this end, we tested if fMRI fluctuations in amygdala functional connectivity (FC) can be related to task-induced changes in physiological arousal and vigilance, as reflected in the skin conductance level (SCL). Thirty-two healthy individuals participated in the study. For the sliding-window analysis we used windows that were shifted by one volume at a time...
March 12, 2017: NeuroImage
https://www.readbyqxmd.com/read/28292717/test-retest-reproducibility-of-quantitative-binding-measures-of-11-c-ro15-4513-a-pet-ligand-for-gabaa-receptors-containing-alpha5-subunits
#20
Colm J McGinnity, Daniela A Riaño Barros, Lula Rosso, Mattia Veronese, Gaia Rizzo, Alessandra Bertoldo, Rainer Hinz, Federico E Turkheimer, Matthias J Koepp, Alexander Hammers
INTRODUCTION: Alteration of γ-aminobutyric acid "A" (GABAA) receptor-mediated neurotransmission has been associated with various neurological and psychiatric disorders. [(11)C]Ro15-4513 is a PET ligand with high affinity for α5-subunit-containing GABAA receptors, which are highly expressed in limbic regions of the human brain (Sur et al., 1998). We quantified the test-retest reproducibility of measures of [(11)C]Ro15-4513 binding derived from six different quantification methods (12 variants)...
March 11, 2017: NeuroImage
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