Linshan Xie^1,2, Xunda Wang^1,2, Teng Ma^1,2,3, Hang Zeng^1,2, Junjian Wen^1,2, Peng Cao³, Ed X. Wu^1,2,4, and Alex T.L. Leong^1,2
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China, ²Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China, ³Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China, ⁴School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China

Keywords: fMRI (task based), fMRI (task based)

Short single pulse stimulation is advantageous to map the downstream neural targets compared to pulse train stimulation because it can minimize the excessive neural synchronization and avoid numerous series of complex neural events. It is desirable for fMRI studies to investigate the properties of neural circuits via delivering single pulse stimulation.  However, the subtle BOLD responses evoked by short stimuli are hard to detect due to the sensitivity issue. Here, we employed fMRI to examine the long-range downstream targets of the somatosensory thalamus with 10ms single pulse stimulation. A model-free fMRI analysis was utilized to visualize the spatiotemporal activity propagation. 

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Won Beom Jung^1,2, Soowon Lee³, Geun Ho Im¹, Taeyi You¹, Eunjoon Kim^4,5, and Seong-Gi Kim^1,6
1Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Korea, Republic of, ²Medical Imaging AI Research Center, Canon Medical Systems Korea, Seoul, Korea, Republic of, ³Graduate School of Medical Science and Engineering,, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, Republic of, ⁴Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon, Korea, Republic of, ⁵Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon, Korea, Republic of, ⁶Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of

Keywords: fMRI (task based), Animals

The fMRI mapping with selective modulation of local neural population at the manipulated region is a powerful approach that can causally link circuit-specific interactions to behavioral performance. However, most fMRI studies combined with chemogenetics were conducted in the resting state, which is difficult to elucidate whether and how differences in functional activity by neuromodulation induce behavioral changes. Here, we demonstrated the effects of fMRI-guided focal chemogenetic modulation on both somatosensory-evoked network and its relevant behaviors in mice.

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Shota Hodono¹, Jonathan R Polimeni^2,3, and Martijn A Cloos^1
1Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia, ²Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ³Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

Keywords: fMRI (task based), Diffusion/other diffusion imaging techniques

We investigated the impact of the EPI readout duration on the onset time of activation observed with diffusion functional MRI (DfMRI).  Both long (28.5-ms) and short (12.5-ms) readouts showed a clear functional response, even in individual subjects. However, using a long readout the onset time was shifted towards SE-BOLD (1.6-s [short readout] vs 1.2-s [long readout]), suggesting that longer readouts make the DfMRI signal more similar to SE-BOLD, presumably due to increased BOLD contamination.

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Keywords: Brain Connectivity, fMRI (task based), hemodynamic response, high temporal resolution, visual cortex

We demonstrate the feasibility and robustness of a new method to measure blood-oxygen-level-dependent functional MRI(BOLD-fMRI) signals at high temporal resolutions(up to 250ms).  Whole-brain data at 1x1x1 mm3 were acquired uninterruptedly during a blocked-design ON/OFF visual paradigm(checkerboard vs. grey image). Images were reconstructed with a 4D x-y-z-t dimensions at 2.5s, 1.0s, 500ms and 250ms temporal resolution, allowing to retrieve the expected %signal change(2%) in visual cortices. We also evaluated the effect of compressed-sensing(CS) application in BOLD-fMRI reconstruction schemes, finding that CS improves the obtained signal in the calcarine sulcus(around 23k(a.u) in pixel intensity of BOLD map TCFE corrected vs 10k(a.u)).

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Elizabeth G. Keeling^1,2, Maurizio Bergamino¹, Sudarshan Ragunathan^1,3, C. Chad Quarles^1,4, and Ashley M. Stokes^1
1Barrow Neurological Institute, Phoenix, AZ, United States, ²Arizona State University, Tempe, AZ, United States, ³Hyperfine, Inc., Guilford, CT, United States, ⁴MD Anderson Cancer Center, Houston, TX, United States

Keywords: Data Acquisition, fMRI (task based), Neuro, multi-echo, multi-contrast, EPI

Standard functional MRI (fMRI) suffers from susceptibility-induced dropout near air-tissue interfaces and is sensitive to larger vessels. Conversely, a combined spin- and gradient-echo (SAGE) acquisition can provide sensitivity to functional activation across macro- and microvascular scales with reduced signal dropout. Multi-echo analysis of SAGE-fMRI data was performed by using quantitative and relaxation-weighted T₂^* and T₂. In a task-based experiment, SAGE relaxation-weighted analyses showed increased contrast- and temporal signal-to-noise ratios (CNR and tSNR, respectively), especially for microvascular analysis. SAGE-fMRI provides improvements over standard fMRI in image quality and robustness of functional activation, as well as inclusion of microvascular sensitivity.

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Antonio Maria Chiarelli¹, Eleonora Patitucci², Michael Germuska³, Alessandra Stella Caporale¹, Emma Biondetti⁴, Hannah Chandler³, Kevin Murphy⁵, Valentina Tomassini^4,5, and Richard Goeffrey Wise^4,5
1Neuroscience, Imaging and Clinical Sciences, University G. D'Annunzio of Chieti Pescara, Chieti Scalo, Italy, ²Department of Psychology, Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff, United Kingdom, ³School of Psychology, Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff, United Kingdom, ⁴University G. D'Annunzio of Chieti Pescara, Chieti Scalo, Italy, ⁵Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff, United Kingdom

Keywords: fMRI (resting state), Quantitative Imaging, Cerebrovascular Reactivity

BOLD and ASL CBF fMRI can measure cerebrovascular reactivity (CVR) following a vasodilatory stimulus such as hypercapnia. BOLD and ASL CVR measurements allow us to extract the maximum BOLD signal modulation from which, through biophysical modelling, OEF and CMRO₂ can be inferred. We measured these physiological variables in grey matter by assessing the resting-state coupling between fMRI and end-tidal CO₂ (reflecting arterial CO₂) recordings. In-vivo evaluation of two, sequentially acquired, 14-min recordings at rest demonstrated the method’s good repeatability. This simplified calibrated fMRI approach does not require an exogenous hypercapnic stimulus and thus holds promise for future applications.

Hanqi Xing¹, Zhiwei Wu¹, Mengya Ma¹, Ziyang Song¹, Yang Song², Yunzhu Wu², Yue Chang¹, and Hui Dai^1
1The First Affiliated Hospital of Soochow University, Suzhou, China, ²MR Scientific Marketing, Siemens Healthcare, Shanghai China., Shanghai, China

Keywords: fMRI (resting state), Brain, sleep

Time-dependent neuromodulation mechanisms in human cognitive-behavioral tasks are not yet fully established. The present study aimed to analyze the changes in resting-state functional magnetic resonance imaging (rs-fMRI) blood oxygen level dependent (BOLD) signals over the 24-h day and their correlation with vigilance level. We recruited 20 healthy volunteers to be scanned at six-time points 24 hours a day. Compared to 9:00, 13:00, 17:00, and 21:00h, thalamic BOLD signals increased and vigilance level decreased at 1:00 and 5:00h. We speculate that the BOLD signals increased in the thalamus may represent a compensatory mechanism for maintaining relative vigilance level.

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Lisa C. Krishnamurthy¹, Venkatagiri Krishnamurthy², Fuyixue Wang³, Lawrence L Wald³, and Vince D Calhoun^4
1Georgia State University, Stone Mountain, GA, United States, ²Emory University, Atlanta, GA, United States, ³Harvard University, Combridge, MA, United States, ⁴Georgia State University, Atlanta, GA, United States

Keywords: fMRI (resting state), Brain

A novel analysis of EPTI rsfMRI to assess frequency contributions in unique echoes.

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Omer Burak Demirel^1,2, Luca Vizioli^2,3, Burhaneddin Yaman^1,2, Steen Moeller², Logan Dowdle^2,3, Essa Yacoub², Kamil Ugurbil², and Mehmet Akçakaya^1,2
1Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States, ²Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, ³Department of Neurosurgery, University of Minnesota, Minneapolis, MN, United States

Keywords: fMRI, fMRI

Functional MRI (fMRI) is acquired with simultaneous multi-slice (SMS) imaging and in-plane acceleration to provide sufficient coverage and spatio-temporal resolutions. However, further accelerations are desirable to achieve BRAIN initiative targets. In this work, we investigate self-supervised deep learning reconstruction at 20-fold (SMS×in-plane=5×4) retrospective and prospective accelerations. Results show DL at 20-fold retrospective acceleration is similar to split slice-GRAPPA at 10-fold acceleration. Furthermore, we show that DL method trained on retrospective 20-fold acceleration generalizes well and successfully reconstructs prospectively 20-fold accelerated fMRI data.

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Gianna Nossa¹, Humberto Monsivais¹, Seokkyoon Hong², Taewoong Park², Fethi Sila Erdil¹, Xin Shen³, Ali Caglar Özen⁴, Serhat Ilbey⁴, Mark Chiew⁵, Cecilia Steinwurzel⁶, Zoe Kourtzi⁶, Yen-Yu Ian Shih⁷, and Uzay Emir^1,2
1School of Health Science, Purdue University, West Lafayette, IN, United States, ²Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States, ³Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, ⁴Department of Radiology, Medical Center-University of Freiburg, Freiburg, Germany, ⁵Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, ⁶Department of Psychology, University of Cambridge, Cambridge, United Kingdom, ⁷Biomedical Research Imaging Center, University of North Carolina Chapel Hill, Chapel Hill, NC, United States

Keywords: fMRI (task based), Brain

In this study, we overcome the technological barrier against acquiring submillimeter resolution (~ 0.5 mm) fMRI data at 3T via a novel dual-echo Rosette k-space design. This design results in fine representation of activation maps in two different functional tasks and might be a springboard in neuroimaging by providing a very high-resolution spatiotemporal dynamics of neural networks. The method will be further evolved with the feedback from the MRI community via the github platform as such for the further acceleration, inflow saturation and 3D coverage via 3D sampling and/or multiband approaches.

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Praveen Iyyappan Valsala¹, Philipp Ehses², Marten Veldmann², and Klaus Scheffler^1,3
1Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, ²German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, ³Department of Biomedical Magnetic Resonance, Eberhard Karls University, Tübingen, Germany

Keywords: Data Acquisition, fMRI (task based), bSSFP, Spiral, non-cartesian, sub-millimeter, whole-brain

We explored the spatio-temporal resolution and coverage of bSSFP BOLD contrast using a highly segmented 3D spiral readout. The functional activation maps acquired with the novel functional contrast for full visual field checkerboard stimulus is presented at submillimeter resolutions (0.6 mm³ & 0.8 mm³) and at 1.2 mm³ for whole brain coverage. We also demonstrated rapid slice-selective water excitation using binomial pulses.

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David Hike¹, Xiaochen Liu¹, Zeping Xie^1,2, Bei Zhang¹, Wenchao Yang¹, Alyssa Murstein^1,3, Andy Liu^1,3, Daniel Glen⁴, Richard Reynolds⁴, and Xin Yu^1
1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States, ²School of Traditional Medicine, Southern China University, Guangzhou, China, ³Neuroscience, Boston University, Boston, MA, United States, ⁴NIMH, National Institutes of Health, Bethesda, MD, United States

Keywords: fMRI (task based), Preclinical, Implantable Coil

This study utilizes implantable RF coils affixed to mouse heads which are used as head fixation points to minimize motion and remove B₁-related artifacts due to motion-induced loading change during scanning. This method increases SNR significantly and enables high-resolution EPI-based functional imaging in awake mice at 14T, highlighting both cortical and subcortical activation following visual and whisker stimulation. Furthermore, this high-resolution awake mouse fMRI setup enables high sensitivity to map brain activation from subcortical nuclei and extends the detection of associated brain regions related to the stimulation.

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Igor Fabian Tellez Ceja¹, Thomas Gladytz¹, Ludger Benedikt Starke¹, Karsten Tabelow², Thoralf Niendorf^1,3, and Henning Matthias Reimann^1
1Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrück Center for Molecular Medicine, Berlin, Germany, ²Weierstrass Institute for Applied Analysis and Stochastics, Berlin, Germany, ³Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany

Keywords: High-Field MRI, fMRI

In recent years, fMRI at ultrahigh magnetic field strengths (≥7T) has shifted from group analyses to probing neural processing in the individual brain. Identifying neurosignatures requires detection of BOLD effects with high sensitivity and spatial accuracy. Yet, it remains a challenge to enhance the sensitivity of fMRI for the BOLD effect without blurring the spatial details.  Here, we assess the quality of the Gaussian, spatial adaptive non-local means (SANLM) and the adaptive weights smoothing (AWS) filters by employing a synthetic fMRI dataset as ground truth. AWS provides superior localization of the BOLD activations with high sensitivity at reasonable noise levels.

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Chuanjun Tong^1,2, Yijuan Zou², Yanqiu Feng¹, and Zhifeng Liang^2
1Southern Medical University, Guangzhou, China, ²Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China

Keywords: fMRI, fMRI, cell-type specific optogentics; basal forebrain

Activations of the basal forebrain (BF) were associated with arousal fluctuations¹, and the regulation of the default model network^2,3. However, it remains ambiguous how the cell-type specific BF neurons shape the behavioral performances. We developed an awake mouse fMRI setup with simultaneous cell-type specific optogenetic stimulations in BF. Combined with the anterograde tracing data4, we revealed weak structural-functional correspondence of BF neurons, and demonstrated the cell-type specific BF modulations shaped global functional network organizations supporting behavioral variability. Our results made great sense on the understanding the cerebral regulations and behaviors from BF neurons in a macroscopic whole-brain view.

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Roberta Maria Lorenzi¹, Alice Geminiani¹, Yann Zerlaut², Alain Destexhe³, Claudia A.M. Gandini Wheeler Kingshott^1,4,5, Fulvia Palesi¹, Claudia Casellato¹, and Egidio D'Angelo^1,5
1Department of Brain and Behavioral Sciences, Università di Pavia, Pavia, Italy, ²Institut du Cerveau - Paris Brain Institute, ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France, ³CNRS, Paris-Saclay University, Saclay, France, ⁴Department of Neuroinflammation, UCL Queen Square Institute of Neurology, NMR Research Unit, Queen Square Multiple Sclerosis Centre, London, United Kingdom, ⁵Brain Connectivity Center, IRCCS Mondino Foundation, Pavia, Italy

Keywords: In Silico, New Devices, Mean field

Whole-brain dynamics can be reproduced in silico by simulating Blood Oxygen Level Dependent (BOLD) signals, typically recorded with fMRI, using cortical and subcortical mean-field models, which provide a population-level description of the underlying neuronal dynamics. Notably, a mean-field model specific for the cerebellum is missing given its structural and functional specific properties. We present the first biologically-grounded cerebellar mean-field model optimized on experimental data. Our model reproduces cerebellar activity and synaptic mechanisms characterizing physiological and pathological conditions. The cerebellar mean-field model is a new device ready to be integrated in whole-brain dynamic simulator, improving understanding of brain function and dysfunction.