ISSN# 1545-4428 | Published date: 19 April, 2024
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At-A-Glance Session Detail
   
BOLD Characteristics: Of Mice & Men
Oral
fMRI
Tuesday, 07 May 2024
Nicoll 3
13:30 -  15:30
Moderators: Natalia Petridou & Zhifeng Liang
Session Number: O-72
CME Credit

13:30 Introduction
Natalia Petridou
UMC Utrecht, Netherlands
13:420530.
Single-pulse optogenetic perturbation of thalamo-cortical networks reveals functional architecture of rsfMRI networks
Linshan Xie1,2, Xunda Wang1,2, Xuehong Lin1,2, Teng Ma1,2,3, Junjian Wen1,2, Peng Cao3, Alex T L Leong1,2, and Ed X Wu1,2,4
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, The University of Hong Kong, Hong Kong SAR, China, 4School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China

Keywords: Functional Connectivity, fMRI (resting state), functional connectivity, neuroscience, brain connectivity

Motivation: A current overarching challenge in neuroscience is to establish an integrated understanding of brain circuits and networks, particularly the interactions of neural populations across various spatiotemporal scales that give rise to functions and behavior. 

Goal(s): We posit that dissecting rsfMRI dynamics under direct single-pulse optogenetic modulation of thalamo-cortical networks will reveal critical insights into the functional architecture of rsfMRI networks. 

Approach: We deployed a computational approach (i.e., Gaussian PCA-HMM) to examine the organization of rsfMRI networks before and upon single-pulse stimulation of  thalamus. 

Results: We demonstrated a significant role of the basal forebrain and hypothalamus in regulating the transient dynamics of rsfMRI networks. 

Impact: The ability to directly perturb and model dynamics of rsfMRI networks present an unprecedented opportunity to understand brain-wide and higher-order circuits/networks, and their functions, which are difficult to probe using traditional behavioral and/or cognitive tasks and other neuroimaging approaches.

13:540531.
Biphasic training for awake imaging using a dual-imaging system reveals neurovascular uncoupling and anesthesia effects in healthy mice
Francesca Mandino1, Xilin Shen1, Gabriel Desrosiers-Gregoire2, David O'Connor1, Bandhan Mukherjee1, Yonghyun Ha1, An Qu1, John Onofrey1, Xenophon Papademetris1, Mallar Chakravarty2, Stephen M Strittmatter1, and Evelyn Lake1
1Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States, 2McGill, Montreal, QC, Canada

Keywords: Small Animals, Brain Connectivity, awake rodent imaging

Motivation: Most of rodent-fMRI is acquired under anesthesia, to minimize motion and stress. However, anesthesia hinders mouse-to-human translatability, since most of human fMRI is conducted whilst awake.

Goal(s): Here we aim to develop a biphasic protocol for conducting awake rodent-fMRI in mice and simultaneously recording mesoscopic calcium imaging data.

Approach: The animals undergo a first training and a refresher a few weeks later. Brain function is analyzed in simultaneous fMRI and mesoscopic calcium imaging measurements.

Results: Having a refresher training improves motion in the scanner. The two measures of brain function show interesting patterns over time, with partial agreement and some clear disagreement. 

Impact: Rodent-fMRI is typically done under anesthesia to minimize stress and motion. This limits mouse-human translatability (since humans are usually scanned awake). Here, we develop a biphasic approach to train mice to awake imaging, using simultaneous fMRI and Calcium imaging measures. 

14:060532.
The application of multi-modal fMRI to investigate coma induction induced by Endothelin-driven brainstem injury
Weitao Man1,2, Xiaochen Liu1, Zeping Xie1, Lidia Gomez-Cid1, Yuanyuan Jiang1, and Xin Yu1
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 2Department of Neurosurgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China

Keywords: Functional Connectivity, Brain Connectivity

Motivation: This study aimed to create a reproducible coma animal model and develop neuroimaging techniques to illustrate underlying mechanisms during coma induction.

Goal(s): To investigate brain dynamic changes during coma induction and to identify the key regulatory brain regions involved in the process.

Approach: We induced a brainstem coma in rats, optimizing surgical procedures and utilizing multi-modal fMRI techniques. We recorded Glu signals and BOLD fMRI simultaneously during coma induction.

Results: The study revealed specific Glu-oscillations before coma induction and identified certain subcortical nuclei as potential key regulatory brain regions for inducing coma. These findings could enhance our understanding of coma-related brain state changes.

Impact: The optimized coma model and multi-modal imaging techniques in this study offer a deeper understanding of coma dynamics. The identification of specific regulatory brain regions and Glutamate oscillations may pave the way for improved clinical strategies and patient outcomes.

14:180533.
Whisker pad stimulation elicits brain-wide cross-sensory activation in awake rats measured with zero echo time fMRI
Jaakko Paasonen1, Juha Valjakka1,2, Raimo A Salo1, Ekaterina Paasonen1, Shalom Michaeli2, Silvia Mangia2, and Olli Gröhn1
1A.I.V Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland, 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Keywords: Task/Intervention Based fMRI, fMRI (task based), awake, rat, multisensory

Motivation: Sensory research has typically focused on one system at a time, and basic mechanisms related to interactions between sensory systems remain poorly understood.

Goal(s): To detect and characterize brain-wide cross-sensory interplay, and to study how non-core circuits react to varying input into the core circuit.

Approach: Classical whisker pad stimulation in head-fixed awake and anesthetized rats in combination with a large number of fMRI measurements.

Results: We detected cross-sensory brain-wide activations to whisker pad stimulation. The activation profile of many non-core regions differed from that of the core circuit. Importantly, some features of cross-sensory interplay were not visible under anesthesia.

Impact: Cross-sensory activations are gaining increasing attention in imaging studies. Previously, multisensory interplay may have gone unnoticed, as the focus has been in the primary pathway. Our results also emphasize the importance of avoiding anesthesia in preclinical cross-sensory research.

14:300534.
Bebop-EPI (BEeping BOld Pulse sequence) – employing inherent acquisition acoustics to generate auditory stimuli for auditory fMRI
Rita Schmidt1 and Amir Seginer2
1Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel, 2Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel

Keywords: fMRI Acquisition, fMRI (task based), Auditory stimuli

Motivation: With improved scanning methods and SNR, auditory response studies in functional MRI require well-defined stimuli but are encumbered by the acoustic noise from the acquisition gradients and by the temporal inaccuracy of the external audio source.

Goal(s): Our goal was to use the acoustic noise generated by the MRI gradients to circumvent an external source for auditory fMRI.

Approach: We implemented BEBOP (BEeping BOld Pulse sequence) EPI which enables varying the echo spacing, and thus pitch,  per slice and per repetition and so provides a platform for auditory fMRI.

Results: An fMRI feasibility study at 7T was successfully implemented, measuring auditory-motor responses.

Impact: We demonstrated a new approach that simultaneously generates auditory stimuli and measures their BOLD response. The new approach offers high temporal accuracy of the auditory tasks due to the MRI gradients’ high temporal precision.

14:420535.
Measure the synchrony of fMRI signals on group-averaged fiber architectures
Yuhao Chen1,2, Luying Li3, Huilou Liang4, Miaoqi Zhang4, Wenjing Zhang1,2, Su Lui1,2, Zhipeng Yang3, and Yu Zhao1,2
1Department of Radiology and Huaxi MR Research Center (HMRRC), Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, Sichuan, China, 2Research Unit of Psychoradiology, Chinese Academy of Medical Sciences, Chengdu, Sichuan, China, 3College of Electronic Engineering, Chengdu University of Information Technology, Chengdu, Sichuan, China, 4GE HealthCare MR Research, Beijing, China

Keywords: fMRI Analysis, Data Analysis, Synchrony

Motivation: Fiber architecture-informed synchrony mapping (FAISM) has been proposed to capture task-evoked nonlinear brain activations, which involves image acquisitions of fMRI and high angular resolution diffusion image MRI (HARDI) with a long scan time and thus limits its applications.

Goal(s): The aim of this study is to modify the FAISM approach to mapping brain activation without time-consuming acquisitions of the HARDI data.

Approach: Hence, group-averaged fiber structures were used to replace the individual data to perform a fast FAISM.

Results: This approach demonstrates a high reproducibility at an individual level, which suggests that it can be used for reliable detections of nonlinear brain activation.

Impact: This approach is expected to serve as a standardized tool to measure neural activations with nonlinear hemodynamic responses.

14:540536.
Investigating timing of BOLD fMRI responses in individual cortical vessels to short and long stimulus durations
Divya Varadarajan1,2, Sebastien Proulx1,2, Paul Wighton1,2, Zhangxuan Hu1,2, Jingyuan E Chen1,2, Saskia Bollmann3, Avery J. L. Berman4, and Jonathan R. Polimeni1,2,5
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital,, Charlestown, MA, United States, 2Radiology, Harvard Medical School, Boston, MA, United States, 3The University of Queensland, St Lucia, Australia, 4Physics, Carleton University, Ottawa, ON, Canada, 5Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology,, Cambridge, MA, United States

Keywords: fMRI Acquisition, fMRI, Vessels, Vascular, Gray Matter, Oxygenation, fMRI (task based), fMRI Acquisition, fMRI Analysis, Hemodynamics

Motivation: Typical fMRI data observes hemodynamics from multiple vascular compartments in each voxel, however understanding the link between neuronal and vascular dynamics will require vessel-specific measurements.

Goal(s): To investigate the timing and amplitude of hemodynamic responses within individual arteries and veins of the human cortex and assess how they change with stimulus duration.

Approach: We applied single-vessel fMRI with multiple echoes to separate inflow and BOLD components, and distinguished intravascular and extravascular dynamics in and around arteries and veins.

Results: We observed faster dynamics in arteries, and a post-stimulus undershoot in all vessels, potentially providing new insights into hemodynamics in the human brain

Impact: Knowledge about hemodynamics within individual vascular compartment is provided by invasive microscopy in small-animal models, and less is known about hemodynamics in humans. Here we present vessel-specific measurements of hemodynamics in humans and reveal unexpected features in the fMRI response.

15:060537.
Assessment of the macrovascular contribution to resting-state fMRI functional connectivity at 3 Tesla
Xiaole Zhong1,2, Yunjie Tong3, and J. Jean Chen1,2,4
1Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, 2Rotman Research Institute at Baycrest, Toronto, ON, Canada, 3Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States, 4Biomedical Engineering, University of Toronto, Toronto, ON, Canada

Keywords: fMRI Analysis, fMRI (resting state)

Motivation: Resting-state fMRI (rs-fMRI) based functional connectivity (fcMRI) is widely used to image neuronal networks, but it could be biased by the contribution of macrovasculature.

Goal(s): This study aims to provide a better understanding of vascular rs-fMRI contributions and their interpretation.

Approach: Our study evaluated macrovascular contributions to experimental rs-fcMRI data.

Results: We found both arteries and veins to substantially modulate fcMRI metrics. We also found that vascular-driven fcMRI spatial variance was disproportionately high given the low vascular voxel count. In particular, veins contribute more to connectivity strength than arteries, while arteries contribute more to spatial variance than veins.

Impact: The macrovasculature was previously shown to modulate functional connectivity and reduce its neuronal specificity, but a systematic analysis is still lacking. This study demonstrates macrovascular contributions at 3 Tesla and paves the way for the correction of bias in rs-fMRI.