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The contribution of astrocytes to the BOLD fMRI and DfMRI responses in visual cortex of mice following visual stimulation was investigated using TGN-020, an aquaporin 4 (AQP4) channel blocker, acting as an astrocyte function perturbator. Under TGN-020 injection the amplitude of the BOLD fMRI response became significantly higher. In contrast no significant changes in the DfMRI responses and the electrophysiological responses were observed. Those results further confirm the implications of astrocytes in the neurovascular coupling mechanism underlying BOLD fMRI, but not in the DfMRI responses which remained unsensitive to astrocyte function perturbation.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241787 | PMC |
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228759 | PLOS |
Stroke
September 2025
Brain Language Laboratory, Freie Universität Berlin, Germany (A.-T.P.J., M.R.O., A.S., F.P.).
Background: Intensive language-action therapy treats language deficits and depressive symptoms in chronic poststroke aphasia, yet the underlying neural mechanisms remain underexplored. Long-range temporal correlations (LRTCs) in blood oxygenation level-dependent signals indicate persistence in brain activity patterns and may relate to learning and levels of depression. This observational study investigates blood oxygenation level-dependent LRTC changes alongside therapy-induced language and mood improvements in perisylvian and domain-general brain areas.
View Article and Find Full Text PDFComput Biol Med
September 2025
Department of Biomedical Engineering, Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden; School of Medical Sciences and Inflammatory Response and Infection Susceptibility Centre (iRiSC), Faculty of Medicine
Functional magnetic resonance imaging (fMRI) is a pivotal tool for mapping neuronal activity in the brain. Traditionally, the observed hemodynamic changes are assumed to reflect the activity of the most common neuronal type: excitatory neurons. In contrast, recent experiments, using optogenetic techniques, suggest that the fMRI-signal could reflect the activity of inhibitory interneurons.
View Article and Find Full Text PDFMagn Reson Med
September 2025
A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland.
Since its introduction more than 30 years ago, the blood oxygenation level-dependent (BOLD) contrast remains the most widely used method for functional MRI (fMRI) in humans and animal models. The BOLD contrast is typically acquired with echo planar imaging (EPI) to obtain sensitization of the signal during the echo time (TE) to dynamic changes in deoxyhemoglobin content, while achieving high spatiotemporal resolution and full brain coverage. However, EPI-based fMRI also faces multiple shortcomings, including sensitivity to body motion, susceptibility-related signal dropouts, interference with multimodal sensors, and loud acoustic noise.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
Department of Psychology, University of Amsterdam, Amsterdam 1018 WS, The Netherlands.
Decision making and learning processes together enable adaptive strategic behavior. Animal studies demonstrated the importance of subcortical regions in these cognitive processes, but the human subcortical contributions remain poorly characterized. Here, we study choice and learning processes in the human subcortex, using a tailored ultra-high field 7T functional MRI protocol combined with joint models.
View Article and Find Full Text PDFMultivariate pattern analysis (MVPA) methods are a versatile tool to retrieve information from neurophysiological data obtained with functional magnetic resonance imaging (fMRI) techniques. Since fMRI is based on measuring the hemodynamic response following neural activation, the spatial specificity of the fMRI signal is inherently limited by contributions of macrovascular compartments that drain the signal from the actual location of neural activation, making it challenging to image cortical structures at the spatial scale of cortical columns and layers. By relying on information from multiple voxels, MVPA has shown promising results in retrieving information encoded in fine-grained spatial patterns.
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