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C R Campos Herrera, G C Beltramini, W M Avelar, F O Lima, L M Li
Differently from previous studies that used Transcranial Doppler (TCD) and functional MRI (fMRI) for cerebral vasomotor reactivity (CVR) assessment in patients with carotid stenosis (CS), we assessed CVR using an identical stimulus, the Breath-Holding Test (BHT). We included 15 patients with CS and 7 age-matched controls to verify whether fMRI responded differently to BHT between groups and to calculate the agreement rate between tests. For TCD, impaired CVR was defined when the mean percentage increase on middle cerebral artery velocities was ≤31% on 3 consecutive 30-s apnea intercalated by 4-min normal breathing intervals...
October 24, 2016: Brazilian Journal of Medical and Biological Research, Revista Brasileira de Pesquisas Médicas e Biológicas
Alexander G Huth, Tyler Lee, Shinji Nishimoto, Natalia Y Bilenko, An T Vu, Jack L Gallant
One crucial test for any quantitative model of the brain is to show that the model can be used to accurately decode information from evoked brain activity. Several recent neuroimaging studies have decoded the structure or semantic content of static visual images from human brain activity. Here we present a decoding algorithm that makes it possible to decode detailed information about the object and action categories present in natural movies from human brain activity signals measured by functional MRI. Decoding is accomplished using a hierarchical logistic regression (HLR) model that is based on labels that were manually assigned from the WordNet semantic taxonomy...
2016: Frontiers in Systems Neuroscience
E Castaldi, G M Cicchini, L Cinelli, L Biagi, S Rizzo, M C Morrone
Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI). After surgery, six out of seven retinitis pigmentosa (RP) blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them...
October 2016: PLoS Biology
Maryna Lapotka, María Ruz, Alberto Salamanca Ballesteros, Olga Ocón Hernández
PURPOSE: This study describes a new methodology-the cold pressor gel test (CPGT)-for delivering an accessible experimental pain stimulus, which is reproducible and safe for functional MRI (fMRI). METHODS: The cold pressor test was modified to put safety precautions into the CPGT. The material used is cool gelled water with a thickening product, which provides a stable temperature at 0.2 °C. Thirteen women with chronic pelvic pain were scanned using a 3 Tesla (T) MR scanner equipped with a 12-channel head coil...
October 25, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Michael Hanke, Nico Adelhöfer, Daniel Kottke, Vittorio Iacovella, Ayan Sengupta, Falko R Kaule, Roland Nigbur, Alexander Q Waite, Florian Baumgartner, Jörg Stadler
Here we present an update of the studyforrest ( dataset that complements the previously released functional magnetic resonance imaging (fMRI) data for natural language processing with a new two-hour 3 Tesla fMRI acquisition while 15 of the original participants were shown an audio-visual version of the stimulus motion picture. We demonstrate with two validation analyses that these new data support modeling specific properties of the complex natural stimulus, as well as a substantial within-subject BOLD response congruency in brain areas related to the processing of auditory inputs, speech, and narrative when compared to the existing fMRI data for audio-only stimulation...
October 25, 2016: Scientific Data
Michael Eickenberg, Alexandre Gramfort, Gaël Varoquaux, Bertrand Thirion
Convolutional networks used for computer vision represent candidate models for the computations performed in mammalian visual systems. We use them as a detailed model of human brain activity during the viewing of natural images by constructing predictive models based on their different layers and BOLD fMRI activations. Analyzing the predictive performance across layers yields characteristic fingerprints for each visual brain region: early visual areas are better described by lower level convolutional net layers and later visual areas by higher level net layers, exhibiting a progression across ventral and dorsal streams...
October 21, 2016: NeuroImage
Jörg Peter Pfannmöller, Marvin Greiner, Mukund Balasubramanian, Martin Lotze
The fingertip somatotopy in BA1 and BA3b of monkeys exhibits characteristic differences with a more discrete separation of the body parts in BA3b and a continuous orientation column like structure in BA1. We present evidence for similar differences in the human somatotopy using BOLD fMRI for the investigations. Though the variability between the individual maps was large, we found a group wide somatotopic representation in BA3b and BA1. The variability due to anatomical differences was small in our sample. This was demonstrated by comparing exact shortest distances in the individual brains and after nonlinear normalization to the group space template, for the removal of the individual anatomical variability...
October 21, 2016: Neuroscience
Richard Baumgartner, William Cho, Alexandre Coimbra, Christopher Chen, Zaiqi Wang, Arie Struyk, Narayanaswamy Venketasubramanian, May Low, Cindy Gargano, Fuqiang Zhao, Donald Williams, Torsten Reese, Stephanie Seah, Dai Feng, Sonya Apreleva, Esben Petersen, Jeffrey L Evelhoch
PURPOSE: To present the testretest and contrast dose effect results of cerebral blood volume (CBV) functional MRI (fMRI) in healthy human volunteers using ferumoxytol (Feraheme), an ultrasmall-superparamagnetic iron oxide (USPIO) nanoparticle. MATERIALS AND METHODS: This was an open-label, two-period, fixed-sequence study in healthy young volunteers. In eight subjects, using a 3 Tesla field strength system, blood oxygen level dependent (BOLD) and CBV fMRI were acquired in response to a visual black-and-white checkboard stimulation paradigm using an escalating ferumoxytol dose design (250, 350, and 510 mg iron)...
October 24, 2016: Journal of Magnetic Resonance Imaging: JMRI
Jaakko Paasonen, Raimo A Salo, Joanna K Huttunen, Olli Gröhn
PURPOSE: Anesthesia is a major confounding factor in functional MRI (fMRI) experiments attributed to its effects on brain function. Recent evidence suggests that parameters obtained with resting-state fMRI (rs-fMRI) are coupled with anesthetic depth. Therefore, we investigated whether parameters obtained with rs-fMRI, such as functional connectivity (FC), are also directly related to blood-oxygen-level-dependent (BOLD) responses. METHODS: A simple rs-fMRI protocol was implemented in a pharmacological fMRI study to evaluate the coupling between hemodynamic responses and FC under five anesthetics (α-chloralose, isoflurane, medetomidine, thiobutabarbital, and urethane)...
October 23, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Mònica Giménez, Andrés Guinea-Izquierdo, Victoria Villalta-Gil, Ignacio Martínez-Zalacaín, Cinto Segalàs, Marta Subirà, Eva Real, Jesús Pujol, Ben J Harrison, Josep Maria Haro, Joao R Sato, Marcelo Q Hoexter, Narcís Cardoner, Pino Alonso, José Manuel Menchón, Carles Soriano-Mas
The extent of functional abnormalities in frontal-subcortical circuits in obsessive-compulsive disorder (OCD) is still unclear. Although neuroimaging studies, in general, and resting-state functional Magnetic Resonance Imaging (rs-fMRI), in particular, have provided relevant information regarding such alterations, rs-fMRI studies have been typically limited to the analysis of between-region functional connectivity alterations at low-frequency signal fluctuations (i.e., <0.08 Hz). Conversely, the local attributes of Blood Oxygen Level Dependent (BOLD) signal across different frequency bands have been seldom studied, although they may provide valuable information...
October 22, 2016: Brain Imaging and Behavior
Tom A Hummer, K Luan Phan, David W Kern, Martha K McClintock
Evidence suggests the putative human pheromone Δ4,16-androstadien-3-one (androstadienone), a natural component of human sweat, increases attention to emotional information when passively inhaled, even in minute amounts. However, the neural mechanisms underlying androstadienone's impact on the perception of emotional stimuli have not been clarified. To characterize how the compound modifies neural circuitry while attending to emotional information, 22 subjects (11 women) underwent two fMRI scanning sessions, one with an androstadienone solution and one with a carrier control solution alone on their upper lip...
September 29, 2016: Psychoneuroendocrinology
Elisa C K Steinfurth, Manuela G Alius, Julia Wendt, Alfons O Hamm
The current experiments tested neural and physiological correlates of worry and rumination in comparison to thinking about neutral events. According to the avoidance model-stating that worry is a strategy to reduce intense emotions-physiological and neurobiological activity during worried thinking should not differ from activation during neutral thinking. According to the contrast avoidance model-stating that worry is a strategy to reduce abrupt shifts of emotions-activity should be increased. To test these competing models, we induced worry and neutral thinking in healthy participants using personal topics...
October 21, 2016: Psychophysiology
Tosoni Annalisa, Guidotti Roberto, Del Gratta Cosimo, Committeri Giorgia, Sestieri Carlo
The human ventral occipito-temporal cortex (OTC) contains areas specialized for particular perceptual/semantic categories, such as faces (fusiform face area, FFA) and places (parahippocampal place area, PPA). This organization has been interpreted as reflecting the visual structure of the world, i.e. perceptual similarity and/or eccentricity biases. However, recent functional magnetic resonance imaging (fMRI) studies have shown not only that regions of the OTC are modulated by non-visual, action-related object properties but also by motor planning and execution, although the functional role and specificity of this motor-related activity are still unclear...
October 15, 2016: Neuropsychologia
Ursula F Bailer, Julie C Price, Carolyn C Meltzer, Angela Wagner, Chester A Mathis, Anthony Gamst, Walter H Kaye
OBJECTIVE: Individuals with anorexia nervosa (AN) have anxious and inhibited temperaments with high concern for consequences. Studies using either positron emission tomography (PET) or functional magnetic resonance imaging (fMRI) suggest involvement of the middle and dorsal caudate (DC) in individuals recovered (REC) from AN. For example, dopamine (DA) D2/D3 receptor binding in the middle caudate and DC was associated with anxiety and harm avoidance, and blood-oxygen-level-dependent (BOLD) response in the DC was positively related to trait anxiety...
October 18, 2016: International Journal of Eating Disorders
J C Pang, P A Robinson, K M Aquino, N Vasan
The effects of astrocytic dynamics on the blood oxygen-level dependent (BOLD) response are modeled. The dynamics are represented via an astrocytic response function that approximates the effects of astrocytic activity, including delay between neural activity and hemodynamic response. The astrocytic response function is incorporated into a spatiotemporal hemodynamic model to predict the BOLD response measured using functional magnetic resonance imaging (fMRI). Adding astrocytic dynamics is shown to significantly improve the ability of the model to robustly reproduce the spatiotemporal properties of the experimental data such as characteristic frequency and time-to-peak...
October 14, 2016: NeuroImage
Zoey J Isherwood, Mark M Schira, Branka Spehar
Natural scenes share a consistent distribution of energy across spatial frequencies (SF) known as the 1/f(α) amplitude spectrum (α ≈ 0.8 - 1.5, mean 1.2). This distribution is scale-invariant, which is a fractal characteristic of natural scenes with statistically similar structure at different spatial scales. While the sensitivity of the visual system to the 1/f properties of natural scenes has been studied extensively using psychophysics, relatively little is known about the tuning of cortical responses to these properties...
October 11, 2016: NeuroImage
Anna Nigri, Eleonora Catricalà, Stefania Ferraro, Maria Grazia Bruzzone, Ludovico D'Incerti, Davide Sattin, Davide Rossi Sebastiano, Silvana Franceschetti, Giorgio Marotta, Riccardo Benti, Matilde Leonardi, Stefano F Cappa
There is a growing interest in the use of functional imaging to assess brain activity in the absence of behavioural responses in patients with disorders of consciousness (DOC). In the present study, we applied a hierarchical auditory stimulation paradigm to functional magnetic resonance (fMRI) in a group of long-term DOC adult patients. Brain response to pairs of pseudowords, of unrelated words and of semantically related words, i.e. stimuli differing in lexical status (words vs. pseudowords) and semantic relatedness (related vs...
October 13, 2016: Brain Imaging and Behavior
Kyriaki Mikellidou, André D Gouws, Hannah Clawson, Peter Thompson, Antony B Morland, Bruce D Keefe
We use the simple, but prominent Helmholtz's squares illusion in which a vertically striped square appears wider than a horizontally striped square of identical physical dimensions to determine whether functional magnetic resonance imaging (fMRI) BOLD responses in V1 underpin illusions of size. We report that these simple stimuli which differ in only one parameter, orientation, to which V1 neurons are highly selective elicited activity in V1 that followed their physical, not perceived size. To further probe the role of V1 in the illusion and investigate plausible extrastriate visual areas responsible for eliciting the Helmholtz squares illusion, we performed a follow-up transcranial magnetic stimulation (TMS) experiment in which we compared perceptual judgments about the aspect ratio of perceptually identical Helmholtz squares when no TMS was applied against selective stimulation of V1, LO1, or LO2...
September 2016: I-Perception
Gang Chen, Paul A Taylor, Robert W Cox
Here we address an important issue that has been embedded within the neuroimaging community for a long time: the absence of effect estimates in results reporting in the literature. The statistic value itself, as a dimensionless measure, does not provide information on the biophysical interpretation of a study, and it certainly does not represent the whole picture of a study. Unfortunately, in contrast to standard practice in most scientific fields, effect (or amplitude) estimates are usually not provided in most results reporting in the current neuroimaging publications and presentations...
October 8, 2016: NeuroImage
Paula L Croal, Ian D Driver, Susan T Francis, Penny A Gowland
The relationship between venous blood oxygenation and change in transverse relaxation rate (ΔR2(⁎)) plays a key role in calibrated BOLD fMRI. This relationship, defined by the parameter β, has previously been determined using theoretical simulations and experimental measures. However, these earlier studies have been confounded by the change in venous cerebral blood volume (CBV) in response to functional tasks. This study used a double-echo gradient echo EPI scheme in conjunction with a graded isocapnic hyperoxic sequence to assess quantitatively the relationship between the fractional venous blood oxygenation (1-Yv) and transverse relaxation rate of grey matter (ΔR2(⁎)GM), without inducing a change in vCBV...
October 5, 2016: NeuroImage
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