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1,586 results on '"Gruetter, Rolf"'

405. Protective effects of maternal nutritional supplementation with lactoferrin on growth and brain metabolism

Author

Somm, Emmanuel, primary, Larvaron, Pierre, additional, van de Looij, Yohan, additional, Toulotte, Audrey, additional, Chatagner, Alexandra, additional, Faure, Magali, additional, Métairon, Sylviane, additional, Mansourian, Robert, additional, Raymond, Frédéric, additional, Gruetter, Rolf, additional, Wang, Bing, additional, Sizonenko, Stéphane V., additional, and Hüppi, Petra S., additional

Published
2013
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420. Genetic Polymorphism Associated Prefrontal Glutathione and Its Coupling With Brain Glutamate and Peripheral Redox Status in Early Psychosis.

Author

Lijing Xin, Mekle, Ralf, Fournier, Margot, Baumann, Philipp S., Ferrari, Carina, Alameda, Luis, Jenni, Raoul, Huanxiang Lu, Schaller, Benoit, Cuenod, Michel, Conus, Philippe, Gruetter, Rolf, and Do, Kim Q.

Subjects
PSYCHOSES, GENETIC polymorphisms, GLUTATHIONE, NUCLEAR magnetic resonance spectroscopy, OXIDATION-reduction reaction, PSYCHOLOGICAL tests, GENETICS
Published
2016
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421. 3D T-weighted imaging at 7T using dynamic k-points on single-transmit MRI systems.

Author

Eggenschwiler, Florent, O'Brien, Kieran, Gallichan, Daniel, Gruetter, Rolf, and Marques, José

Subjects
MAGNETIC resonance imaging, ECHO, STRUCTURAL acoustics
Abstract

Objectives: For turbo spin echo (TSE) sequences to be useful at ultra-high field, they should ideally employ an RF pulse train compensated for the B inhomogeneity. Previously, it was shown that a single k-point pulse designed in the small tip-angle regime can replace all the pulses of the sequence (static k-points). This work demonstrates that the B dependence of T-weighted imaging can be further mitigated by designing a specific k-point pulse for each pulse of a 3D TSE sequence (dynamic k-points) even on single-channel transmit systems Materials and methods: By combining the spatially resolved extended phase graph formalism (which calculates the echo signals throughout the sequence) with a gradient descent algorithm, dynamic k-points were optimized such that the difference between the simulated signal and a target was minimized at each echo. Dynamic k-points were inserted into the TSE sequence to acquire in vivo images at 7T. Results: The improvement provided by the dynamic k-points over the static k-point design and conventional hard pulses was demonstrated via simulations. Images acquired with dynamic k-points showed systematic improvement of signal and contrast at 7T over regular TSE-especially in cerebellar and temporal lobe regions without the need of parallel transmission. Conclusion: Designing dynamic k-points for a 3D TSE sequence allows the acquisition of T-weighted brain images on a single-transmit system at ultra-high field with reduced dropout and only mild residual effects due to the B inhomogeneity. [ABSTRACT FROM AUTHOR]

Published
2016
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422. Three-dimensional echo planar imaging with controlled aliasing: A sequence for high temporal resolution functional MRI.

Author

Narsude, Mayur, Gallichan, Daniel, van der Zwaag, Wietske, Gruetter, Rolf, and Marques, José P.

Abstract

Purpose In this work, we combine three-dimensional echo planar imaging (3D-EPI) with controlled aliasing to substantially increase temporal resolution in whole-brain functional MRI (fMRI) while minimizing geometry-factor (g-factor) losses. Theory and Methods The study was performed on a 7 Tesla scanner equipped with a 32-channel receive coil. The proposed 3D-EPI-CAIPI sequence was evaluated for: (i) image quality, compared with a conventionally undersampled parallel imaging acquisition; (ii) temporal resolution, the ability to sample and remove physiological signal fluctuations from the fMRI signal of interest and (iii) the ability to distinguish small changes in hemodynamic responses in an event-related fMRI experiment. Results Whole-brain fMRI data with a voxel size of 2 × 2 × 2 mm3 and temporal resolution of 371 ms could be acquired with acceptable image quality. Ten-fold parallel imaging accelerated 3D-EPI-CAIPI data were shown to lower the maximum g-factor losses up to 62% with respect to a 10-fold accelerated 3D-EPI dataset. FMRI with 400 ms temporal resolution allowed the detection of time-to-peak variations in functional responses due to multisensory facilitation in temporal, occipital and frontal cortices. Conclusion 3D-EPI-CAIPI allows increased temporal resolution that enables better characterization of physiological noise, thus improving sensitivity to signal changes of interest. Furthermore, subtle changes in hemodynamic response dynamics can be studied in shorter scan times by avoiding the need for jittering. Magn Reson Med 75:2350-2361, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Published
2016
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424. Quantitative activity-induced manganese-dependent MRI for characterizing cortical layers in the primary somatosensory cortex of the rat.

Author

Auffret, Matthieu, Samim, Idrees, Lepore, Mario, Gruetter, Rolf, and Just, Nathalie

Subjects
PHYSIOLOGICAL effects of manganese, MAGNETIC resonance imaging of the brain, CEREBRAL cortex, SOMATOSENSORY cortex, LABORATORY rats
Abstract

The ability of Mn to follow Ca pathways upon stimulation transform them into remarkable surrogate markers of neuronal activity using activity-induced manganese-dependent MRI (AIM-MRI). In the present study, a precise follow-up of physiological parameters during MnCl and mannitol infusions improved the reproducibility of AIM-MRI allowing in-depth evaluation of the technique. Pixel-by-pixel T data were investigated using histogram distributions in the barrel cortex (BC) and the thalamus before and after Mn infusion, after blood brain barrier opening and after BC activation. Mean BC T values dropped significantly upon trigeminal nerve (TGN) stimulation (−38 %, P = 0.02) in accordance with previous literature findings. T histogram distributions showed that 34 % of T in the range 600-1500 ms after Mn+ mannitol infusions shifted to 50-350 ms after TGN stimulation corresponding to a twofold increase of the percentage of pixels with the lowest T in BC. Moreover, T changes in response to stimulation increased significantly from superficial cortical layers (I-III) to deeper layers (V-VI). Cortical cytoarchitecture detection during a functional paradigm was performed extending the potential of AIM-MRI. Quantitative AIM-MRI could thus offer a means to interpret local neural activity across cortical layers while identification of the role of calcium dynamics in vivo during brain activation could play a key role in resolving neurovascular coupling mechanisms. [ABSTRACT FROM AUTHOR]

Published
2016
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425. Glutathione Deficit Affects the Integrity and Function of the Fimbria/Fornix and Anterior Commissure in Mice: Relevance for Schizophrenia.

Author

Corcoba, Alberto, Steullet, Pascal, Duarte, João M. N., Van de Looij, Yohan, Monin, Aline Monin, Cuenod, Michel, Gruetter, Rolf, and Do, Kim Q.

Subjects
SCHIZOPHRENIA, PATHOLOGICAL psychology, BIPOLAR disorder, DIFFUSION tensor imaging, OXIDATIVE stress, GLUTATHIONE
Abstract

Background: Structural anomalies of white matter are found in various brain regions of patients with schizophrenia and bipolar and other psychiatric disorders, but the causes at the cellular and molecular levels remain unclear. Oxidative stress and redox dysregulation have been proposed to play a role in the pathophysiology of several psychiatric conditions, but their anatomical and functional consequences are poorly understood. The aim of this study was to investigate white matter throughout the brain in a preclinical model of redox dysregulation. Methods: In a mouse model with impaired glutathione synthesis (Gclm KO), a state-of-the-art multimodal magnetic resonance protocol at high field (14.1 T) was used to assess longitudinally the white matter structure, prefrontal neurochemical profile, and ventricular volume. Electrophysiological recordings in the abnormal white matter tracts identified by diffusion tensor imaging were performed to characterize the functional consequences of fractional anisotropy alterations. Results: Structural alterations observed at peri-pubertal age and adulthood in Gclm KO mice were restricted to the anterior commissure and fornix-fimbria. Reduced fractional anisotropy in the anterior commissure (-7.5% ± 1.9, P < .01) and fornixfimbria (-4.5% ± 1.3, P < .05) were accompanied by reduced conduction velocity in fast-conducting fibers of the posterior limb of the anterior commissure (-14.3% ± 5.1, P < .05) and slow-conducting fibers of the fornix-fimbria (-8.6% ± 2.6, P < .05). Ventricular enlargement was found at peri-puberty (+25% ± 8 P < .05) but not in adult Gclm KO mice. Conclusions: Glutathione deficit in Gclm KO mice affects ventricular size and the integrity of the fornix-fimbria and anterior commissure. This suggests that redox dysregulation could contribute during neurodevelopment to the impaired white matter and ventricle enlargement observed in schizophrenia and other psychiatric disorders. [ABSTRACT FROM AUTHOR]

Published
2016
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432. Deletion of glutamate dehydrogenase 1 (Glud1) in the central nervous system affects glutamate handling without altering synaptic transmission

Author

Frigerio, Francesca, primary, Karaca, Melis, additional, De Roo, Mathias, additional, Mlynárik, Vladimír, additional, Skytt, Dorte M., additional, Carobbio, Stefania, additional, Pajęcka, Kamilla, additional, Waagepetersen, Helle S., additional, Gruetter, Rolf, additional, Muller, Dominique, additional, and Maechler, Pierre, additional

Published
2012
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