Principles of intensive human neuroimaging

Trends in Neurosciences, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 1, 2024

Language: Английский

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Mapping curvature domains in human V4 using CBV-sensitive layer-fMRI at 3T

Frontiers in Neuroscience, Journal Year: 2025, Volume and Issue: 19

Published: Feb. 26, 2025

A full understanding of how we see our world remains a fundamental research question in vision neuroscience. While topographic profiling has allowed us to identify different visual areas, the exact functional characteristics and organization areas up hierarchy (beyond V1 & V2) is still debated. It hypothesized that area V4 represents vital intermediate stage processing spatial curvature information preceding object recognition. Advancements magnetic resonance imaging hardware acquisition techniques (e.g., non-BOLD MRI) now permits capture cortical layer-specific properties human brain (including system) at high precision. Here, use cerebral blood volume measures study modularity responses contours (curvature) are organized within brain. To achieve this 3 Tesla (a clinically relevant field strength) utilize optimized high-resolution 3D-Echo Planar Imaging (EPI) Vascular Space Occupancy (VASO) measurements. Data here provide first evidence domains consistent with previous findings from non-human primates. We show VASO BOLD tSNR maps for align equivalents, robust time series changes stimuli measured across cortex. preference strong modular compared contrast. noted much lower sensitivity (due known venous vasculature weightings) specificity stimulus persist depth. The work advances role mid-level shape features. Knowledge architecture hierarchical integration local contribute formation shapes can inform computational models Techniques described allow quantification individual differences help drive better relate difference perception.

Language: Английский

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A 128‐channel receive array with enhanced signal‐to‐noise ratio performance for 10.5T brain imaging

Magnetic Resonance in Medicine, Journal Year: 2025, Volume and Issue: unknown

Published: March 13, 2025

Abstract Purpose To develop and characterize a 128‐channel head array for brain imaging at 10.5 T, evaluate signal‐to‐noise ratio (SNR) relative to ultimate intrinsic SNR (uiSNR) lower field strengths, demonstrate human anatomical functional with this unique magnetic high‐channel‐count array. Methods The coil consists of 16‐channel self‐decoupled loop transmit/receive (16Tx/Rx) 112‐loop receive‐only (Rx) insert. Interactions between the 16Tx/Rx 112Rx insert were mitigated using coaxial cable traps placed every 1/16 wavelength on each feed cable, locating most preamplifier boards outside transmitter field, miniaturizing those directly individual coils. Results effect circumscribing was minimized, leading similar transmit maps obtained experimentally without in place by electromagnetic simulations alone. captured 77% uiSNR centrally. Significantly higher 1/g‐factor values across whole achieved compared 7 T. Excellent SNR, high parallel‐imaging performance, minimal Tx‐Rx interactions collectively facilitated acquisition high‐quality, high‐resolution, proof‐of‐concept images, including power‐demanding sequences brain. Conclusions Counterintuitive expectations based fields less than or equal channel counts provided gains centrally, capturing about 80% uiSNR. fraction centrally 64Rx, 80Rx, 128Rx arrays suggested that plateau being reached 80%. At plateau, B 0 ‐dependent T approximately linear quadratic periphery center, respectively.

Language: Английский

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Open-transmit and flexible receiver array for high resolution ultrahigh-field fMRI of the human sensorimotor cortex

Communications Biology, Journal Year: 2025, Volume and Issue: 8(1)

Published: March 22, 2025

In this study, we developed an open-transmit and 24-channel flexible receiver head coil assembly tailored for high-resolution ultrahigh-field functional magnetic resonance imaging (fMRI) of the human somatosensory motor cortex. Leveraging increased signal-to-noise ratio (SNR) spatial resolution ultrahigh field MRI, address technical challenges inherent in fMRI design. The open-birdcage transmit enhances patient comfort enables visual task implementation, demonstrating superior performance efficiency specific absorption rate distribution compared to conventional coils. Furthermore, offers enhanced SNR image quality, facilitating sub-millimeter vascular-space-occupancy precise mapping. These advancements provide valuable tools unraveling intricacies cortex function. By enriching brain studies, they contribute significantly our understanding mechanisms underlying function may have clinical applications neurology neuroscience research. An fMRI, enabling mapping, advancing

Language: Английский

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Laminar VASO fMRI in focal hand dystonia patients

Dystonia, Journal Year: 2023, Volume and Issue: 2

Published: Feb. 1, 2023

Focal Hand Dystonia (FHD) is a disabling movement disorder characterized by involuntary movements, cramps and spasms. It associated with pathological neural microcircuits in the cortical somatosensory system. While invasive preclinical modalities allow researchers to probe specific of layers columns, conventional functional magnetic resonance imaging (fMRI) cannot resolve such small computational units. In this study, we take advantage recent developments ultra-high-field MRI hardware MR-sequences capture altered digit representations laminar processing FHD patients. We aim characterize capability challenges layer-specific analysis tools resolving columnar structures clinical research setups. scanned N = 4 affected 5 unaffected hemispheres at 7T found consistent results microcircuitry patients: 1) patients, breakdown ordered finger representation primary cortex, as suggested from previous low-resolution fMRI. 2) motor cortices furthermore increased fMRI activity superficial cortico-cortical input (II/III), compared relatively weaker cortico-spinal output (Vb/VI). Overall, show that layer-fMRI acquisition have potential address clinically-driven neuroscience questions about mechanisms spatial scales were previously only accessible animal models. believe study paves way for easier translation work into focal hand dystonia beyond.

Language: Английский

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Segmentation of supragranular and infragranular layers in ultra-high-resolution 7T ex vivo MRI of the human cerebral cortex

Cerebral Cortex, Journal Year: 2024, Volume and Issue: 34(9)

Published: Aug. 19, 2024

Accurate labeling of specific layers in the human cerebral cortex is crucial for advancing our understanding neurodevelopmental and neurodegenerative disorders. Building on recent advancements ultra-high-resolution ex vivo MRI, we present a novel semi-supervised segmentation model capable identifying supragranular infragranular MRI with unprecedented precision. On dataset consisting 17 whole-hemisphere scans at 120 $\mu $m, propose Multi-resolution U-Nets framework that integrates global local structural information, achieving reliable maps entire hemisphere, Dice scores over 0.8 supra- layers. This enables surface modeling, atlas construction, anomaly detection disease states, cross-modality validation while also paving way finer layer segmentation. Our approach offers powerful tool comprehensive neuroanatomical investigations holds promise mechanistic progression diseases.

Language: Английский

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In the brain of the beholder: bi-stable motion reveals mesoscopic-scale feedback modulation in V1

Brain Structure and Function, Journal Year: 2025, Volume and Issue: 230(3)

Published: April 5, 2025

Abstract Understanding the neural processes underlying conscious perception remains a central goal in neuroscience. Visual illusions, whether static or dynamic, provide an effective ecological paradigm for studying perception, as they induce subjective experiences from constant visual inputs. While previous neuroimaging studies have dissociated perceptual interpretation of motion sensory input within motion-sensitive area (hMT+) humans, less is known about role primary (V1) and its relationship to hMT+ during bistable perception. To address this, we conducted layer-fMRI study at 7 T with human participants exposed quartet stimulus. Despite input, elicits switching horizontal vertical apparent percepts likely due lateral feedback connections across low high-level brain regions (feedback processing). As control, used “unambiguous” version quartet, hereafter referred “physical” stimulus, where physically presented stimulus alternated fashion (feedforward With advantage sub-millimeter resolution gained ultra-high magnetic field (7 Tesla), aimed unveil differential laminar modulation V1 (early area) (high-order physical condition. Our results indicate that: (1) functional activity correlates both ambiguous stimuli similar strength. There no evidence profiles between two experimental conditions. (2) Between inducer squares, shows significantly reduced response compared it primarily reflects signals diminished feedforward input. Distinct differentiate (3) The temporal dynamics become more (4) exhibits specificity condition retinotopic locations corresponding perceived motion. findings demonstrate that condition, there stronger coupling V1. Such might be contributing stabilization vivid directed face stimulation.

Language: Английский

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Effect of motion, cortical orientation and spatial resolution on quantitative imaging of cortical R2* and magnetic susceptibility at 0.3 mm in-plane resolution at 7 T

NeuroImage, Journal Year: 2023, Volume and Issue: 270, P. 119992 - 119992

Published: Feb. 27, 2023

MR images of the effective relaxation rate R2* and magnetic susceptibility χ derived from multi-echo T2*-weighted (T2*w) MRI can provide insight into iron myelin distributions in brain, with potential providing biomarkers for neurological disorders. Quantification at submillimeter resolution cortex vivo has been difficult because challenges such as head motion, limited signal to noise ratio, long scan time, motion related field fluctuations. This work aimed improve robustness quantifying intracortical analyze effects spatial resolution, cortical orientation. T2*w data was acquired a 0.3 × 0.4 mm3 7 T downsampled various lower resolutions. A combined correction B0 changes deployed using volumetric navigators. Such improved image quality rated by experienced readers test-retest reliability quantification reduced median inter-scan differences up 10 s−1 5 ppb, respectively. near line Gennari, layer high myelin, were much ppb higher than region adjacent depth. In addition, significant effect due orientation relative static (B0) observed peak-to-peak amplitude about 17 ppb. retrospectively data, capability distinguish different depth regions based on or contrast remained isotropic 0.5 mm resolution. study highlights unique characteristics along need corrections their robust vivo.

Language: Английский

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Imaging the columnar functional organization of human area MT+ to axis-of-motion stimuli using VASO at 7 Tesla

Cerebral Cortex, Journal Year: 2023, Volume and Issue: 33(13), P. 8693 - 8711

Published: May 30, 2023

Abstract Cortical columns of direction-selective neurons in the motion sensitive area (MT) have been successfully established as a microscopic feature neocortex animals. The same property has investigated at mesoscale (<1 mm) homologous brain (hMT+, V5) living humans by using ultra-high field functional magnetic resonance imaging (fMRI). Despite reproducibility selective response to axis-of-motion stimuli, clear quantitative evidence for columnar organization hMT+ is still lacking. Using cerebral blood volume (CBV)-sensitive fMRI 7 Tesla with submillimeter resolution and high spatial specificity microvasculature, we investigate 5 participants perceiving stimuli both oxygenation level dependent (BOLD) vascular space occupancy (VASO) contrast mechanisms provided used slice-selective slab-inversion (SS-SI)-VASO sequence. With development new searchlight algorithm column detection, provide first columnarity map that characterizes entire 3D volume. voxel-wise measures sensitivity specificity, demonstrate advantage CBV-sensitive detect mesoscopic cortical features revealing higher VASO compared BOLD contrast. These metrics also further insights on how mitigate highly debated draining veins effect. We conclude CBV–VASO together measurements sensitivity, offers promising avenue quantify respect stimuli. Furthermore, our approach methodological developments are generalizable applicable other human areas where similar research questions addressed.

Language: Английский

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Characterisation of laminar and vascular spatiotemporal dynamics of CBV and BOLD signals using VASO and ME-GRE at 7T in humans

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Jan. 26, 2024

Abstract Interpretation of cortical laminar functional magnetic resonance imaging (fMRI) activity requires detailed knowledge the spatiotemporal haemodynamic response across vascular compartments due to well-known biases (e.g. draining veins). Further complications arise from hemodynamic that differs depending on duration stimulation. This information is crucial for future studies using depth-dependent cerebral blood volume (CBV) measurements, which promise higher specificity microvasculature than oxygenation level dependent (BOLD) contrast. To date, direct about CBV dynamics with respect stimulus duration, depth and vasculature missing in humans. Therefore, we characterized CBV-haemodynamic responses a wide set durations 0.9 mm isotropic spatial 0.785 seconds effective temporal resolution humans slice-selective slabinversion space occupancy (SS-SI VASO). Additionally, investigated signal contributions macrovascular fine-scale multiecho gradient-echo (ME-GRE) data at 0.35 resolution. In total, this resulted > 7.5h scanning per participant (n=5). We have three major findings: (I) While could demonstrate 1 second stimulation viable VASO, more 12 provides better terms microvasculature, but beyond 24 may be wasteful certain applications. (II) observe show dilation patterns cortex. (III) found increasingly strong BOLD vessel-dominated voxels longer durations, only until 4 durations. After seconds, non-vessel dominated kept increasing. might explain why are specific underlying neuronal long

Language: Английский

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