Search results for " Magnetic resonance imaging"
showing 10 items of 452 documents
Multi-band SWIFT enables quiet and artefact-free EEG-fMRI and awake fMRI studies in rat
2020
Functional magnetic resonance imaging (fMRI) studies in animal models provide invaluable information regarding normal and abnormal brain function, especially when combined with complementary stimulation and recording techniques. The echo planar imaging (EPI) pulse sequence is the most common choice for fMRI investigations, but it has several shortcomings. EPI is one of the loudest sequences and very prone to movement and susceptibility-induced artefacts, making it suboptimal for awake imaging. Additionally, the fast gradient-switching of EPI induces disrupting currents in simultaneous electrophysiological recordings. Therefore, we investigated whether the unique features of Multi-Band SWeep…
Comparison of Diffusion MRI Acquisition Protocols for the In Vivo Characterization of the Mouse Spinal Cord: Variability Analysis and Application to …
2016
Diffusion-weighted Magnetic Resonance Imaging (dMRI) has relevant applications in the microstructural characterization of the spinal cord, especially in neurodegenerative diseases. Animal models have a pivotal role in the study of such diseases; however, in vivo spinal dMRI of small animals entails additional challenges that require a systematical investigation of acquisition parameters. The purpose of this study is to compare three acquisition protocols and identify the scanning parameters allowing a robust estimation of the main diffusion quantities and a good sensitivity to neurodegeneration in the mouse spinal cord. For all the protocols, the signal-to-noise and contrast-to noise ratios…
Distributed analysis of simultaneous EEG-fMRI time-series: modeling and interpretation issues
2009
Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) represent brain activity in terms of a reliable anatomical localization and a detailed temporal evolution of neural signals. Simultaneous EEG-fMRI recordings offer the possibility to greatly enrich the significance and the interpretation of the single modality results because the same neural processes are observed from the same brain at the same time. Nonetheless, the different physical nature of the measured signals by the two techniques renders the coupling not always straightforward, especially in cognitive experiments where spatially localized and distributed effects coexist and evolve temporally at different …
Symptom-specific amygdala hyperactivity modulates motor control network in conversion disorder
2016
Initial historical accounts as well as recent data suggest that emotion processing is dysfunctional in conversion disorder patients and that this alteration may be the pathomechanistic neurocognitive basis for symptoms in conversion disorder. However, to date evidence of direct interaction of altered negative emotion processing with motor control networks in conversion disorder is still lacking. To specifically study the neural correlates of emotion processing interacting with motor networks we used a task combining emotional and sensorimotor stimuli both separately as well as simultaneously during functional magnetic resonance imaging in a well characterized group of 13 conversion disorder…
Deep Learning for fully automatic detection, segmentation, and Gleason Grade estimation of prostate cancer in multiparametric Magnetic Resonance Imag…
2021
The emergence of multi-parametric magnetic resonance imaging (mpMRI) has had a profound impact on the diagnosis of prostate cancers (PCa), which is the most prevalent malignancy in males in the western world, enabling a better selection of patients for confirmation biopsy. However, analyzing these images is complex even for experts, hence opening an opportunity for computer-aided diagnosis systems to seize. This paper proposes a fully automatic system based on Deep Learning that takes a prostate mpMRI from a PCa-suspect patient and, by leveraging the Retina U-Net detection framework, locates PCa lesions, segments them, and predicts their most likely Gleason grade group (GGG). It uses 490 mp…
Early emergence of deviant frontal fMRI activity for phonological processes in poor beginning readers.
2010
Phonological awareness refers to the ability to perceive and manipulate the sound structure of language and is especially important when children learn to read. Poor phonological awareness is considered the major cause for the emergence of reading difficulties. In this functional magnetic resonance imaging (fMRI) study, we examined the brain correlates of phonological processing in young beginning readers (aged 8.3+/-0.4 y, 2nd grade) with poor (25th percentile) or normal, age-appropriate reading skills (40th percentile) using a covert reading and mental letter substitution task. Letter substitution in words and nonwords induced pronounced activity in a left frontal language network related…
Reward for food odors: An fMRI study of liking and wanting as a function of metabolic state and BMI
2014
Brain reward systems mediate liking and wanting for food reward. Here, we explore the differential involvement of the following structures for these two components: the ventral and dorsal striatopallidal area, orbitofrontal cortex (OFC), anterior insula, and anterior cingulate. Twelve healthy female participants were asked to rate pleasantness (liking of food and non-food odors) and the desire to eat (wanting of odor-evoked food) during event-related functional magnetic resonance imaging (fMRI). The subjective ratings and fMRI were performed in hunger and satiety states. Activations of regions-of-interest were compared as a function of task (liking vs. wanting), odor category (food vs. non-…
Bone marrow fat quantification of osteoporotic vertebral compression fractures: comparison of multi-voxel proton MR spectroscopy and chemical-shift g…
2011
Background Only a few studies have used in/opposed phase method for a quantitative evaluation of fat fraction in the spine. Purpose To compare multivoxel proton MR spectroscopy and chemical-shift gradient-echo MR imaging for bone marrow fat quantification in vertebral compression fractures (VCF). Material and Methods Vertebral marrow fat quantification in fifteen patients was measured at 3.0-T. Multi-voxel proton spectroscopy (MRS) and in/opposed-phase MR imaging using a fat map build with a triple-echo gradient-echo sequence was used. All the patients had benign vertebral collapse. Bone marrow fat content was evaluated by both techniques in compressed (acute or chronic) and in non-compress…
Embedded word priming elicits enhanced fMRI responses in the visual word form area.
2018
Lexical embedding is common in all languages and elicits mutual orthographic interference between an embedded word and its carrier. The neural basis of such interference remains unknown. We employed a novel fMRI prime-target embedded word paradigm to test for involvement of a visual word form area (VWFA) in left ventral occipitotemporal cortex in co-activation of embedded words and their carriers. Based on the results of related fMRI studies we predicted either enhancement or suppression of fMRI responses to embedded words initially viewed as primes, and repeated in the context of target carrier words. Our results clearly showed enhancement of fMRI responses in the VWFA to embedded-carrier …
Dysfunction of attention switching networks in amyotrophic lateral sclerosis
2019
Objective To localise and characterise changes in cognitive networks in Amyotrophic Lateral Sclerosis (ALS) using source analysis of mismatch negativity (MMN) waveforms. Rationale The MMN waveform has an increased average delay in ALS. MMN has been attributed to change detection and involuntary attention switching. This therefore indicates pathological impairment of the neural network components which generate these functions. Source localisation can mitigate the poor spatial resolution of sensor-level EEG analysis by associating the sensor-level signals to the contributing brain sources. The functional activity in each generating source can therefore be individually measured and investigat…