37 results on '"Bright, Molly G."'
Search Results
2. Comparing end-tidal CO2, respiration volume per time (RVT), and average gray matter signal for mapping cerebrovascular reactivity amplitude and delay with breath-hold task BOLD fMRI
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Zvolanek, Kristina M., Moia, Stefano, Dean, Joshua N., Stickland, Rachael C., Caballero-Gaudes, César, and Bright, Molly G.
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- 2023
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3. Simultaneous cortical, subcortical, and brainstem mapping of sensory activation.
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Reddy, Neha A, Clements, Rebecca G, Brooks, Jonathan C W, and Bright, Molly G
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- 2024
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4. A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function
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Stickland, Rachael C., Zvolanek, Kristina M., Moia, Stefano, Ayyagari, Apoorva, Caballero-Gaudes, César, and Bright, Molly G.
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- 2021
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5. ICA-based denoising strategies in breath-hold induced cerebrovascular reactivity mapping with multi echo BOLD fMRI
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Moia, Stefano, Termenon, Maite, Uruñuela, Eneko, Chen, Gang, Stickland, Rachael C., Bright, Molly G., and Caballero-Gaudes, César
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- 2021
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6. Vascular physiology drives functional brain networks
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Bright, Molly G., Whittaker, Joseph R., Driver, Ian D., and Murphy, Kevin
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- 2020
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7. Multiparametric measurement of cerebral physiology using calibrated fMRI
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Bright, Molly G., Croal, Paula L., Blockley, Nicholas P., and Bulte, Daniel P.
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- 2019
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8. Changes in arterial cerebral blood volume during lower body negative pressure measured with MRI
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Whittaker, Joseph R., Bright, Molly G., Driver, Ian D., Babic, Adele, Khot, Sharmila, and Murphy, Kevin
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- 2019
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9. Spatial distribution of hand‐grasp motor task activity in spinal cord functional magnetic resonance imaging.
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Hemmerling, Kimberly J., Hoggarth, Mark A., Sandhu, Milap S., Parrish, Todd B., and Bright, Molly G.
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FUNCTIONAL magnetic resonance imaging ,SPINAL cord ,OBJECT manipulation ,MUSCLE contraction - Abstract
Upper extremity motor paradigms during spinal cord functional magnetic resonance imaging (fMRI) can provide insight into the functional organization of the cord. Hand‐grasping is an important daily function with clinical significance, but previous studies of similar squeezing movements have not reported consistent areas of activity and are limited by sample size and simplistic analysis methods. Here, we study spinal cord fMRI activation using a unimanual isometric hand‐grasping task that is calibrated to participant maximum voluntary contraction (MVC). Two task modeling methods were considered: (1) a task regressor derived from an idealized block design (Ideal) and (2) a task regressor based on the recorded force trace normalized to individual MVC (%MVC). Across these two methods, group motor activity was highly lateralized to the hemicord ipsilateral to the side of the task. Activation spanned C5–C8 and was primarily localized to the C7 spinal cord segment. Specific differences in spatial distribution are also observed, such as an increase in C8 and dorsal cord activity when using the %MVC regressor. Furthermore, we explored the impact of data quantity and spatial smoothing on sensitivity to hand‐grasp motor task activation. This analysis shows a large increase in number of active voxels associated with the number of fMRI runs, sample size, and spatial smoothing, demonstrating the impact of experimental design choices on motor activation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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10. Ultra-high-field arterial spin labelling MRI for non-contrast assessment of cortical lesion perfusion in multiple sclerosis
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Dury, Richard J., Falah, Yasser, Gowland, Penny A., Evangelou, Nikos, Bright, Molly G., and Francis, Susan T.
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- 2019
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11. Potential pitfalls when denoising resting state fMRI data using nuisance regression
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Bright, Molly G., Tench, Christopher R., and Murphy, Kevin
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- 2017
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12. Early anti-correlated BOLD signal changes of physiologic origin
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Bright, Molly G., Bianciardi, Marta, de Zwart, Jacco A., Murphy, Kevin, and Duyn, Jeff H.
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- 2014
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13. Removing motion and physiological artifacts from intrinsic BOLD fluctuations using short echo data
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Bright, Molly G. and Murphy, Kevin
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- 2013
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14. Editorial: Imaging Cerebrovascular Reactivity: Physiology, Physics and Therapy
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Duffin, James, Bright, Molly G., and Blockley, Nicholas P.
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Editorial ,Physiology ,cerebral blood flow ,carbon dioxide ,magnetic resonance imaging ,cerebrovascular reactivity ,blood oxygenation level dependent signal - Published
- 2021
15. The absolute CBF response to activation is preserved during elevated perfusion: Implications for neurovascular coupling measures
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Whittaker, Joseph R., Driver, Ian D., Bright, Molly G., and Murphy, Kevin
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- 2016
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16. Effects of variability in manually contoured spinal cord masks on fMRI co-registration and interpretation.
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Hoggarth, Mark A., Wang, Max C., Hemmerling, Kimberly J., Vigotsky, Andrew D., Smith, Zachary A., Parrish, Todd B., Weber II, Kenneth A., and Bright, Molly G.
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SPINAL cord ,FUNCTIONAL magnetic resonance imaging ,CEREBROSPINAL fluid - Abstract
Functional magnetic resonance imaging (fMRI) of the human spinal cord (SC) is an emerging but technically challenging method for understanding neurovascular responses to sensory and motor stimuli. Group-analysis of SC fMRI data involves co-registration of subject-level data to a standard image, which currently requires manual masking of the cord. We hypothesize that this manual input may contribute to bias or poor repeatability in group-level SC fMRI results. To test this, we examined variability in SC masks drawn in fMRI data from 21 healthy participants taken from a completed study mapping responses to sensory stimuli of the C7 dermatome. Masks were drawn on the temporal mean functional image by eight raters with varying levels of neuroimaging experience, and the rater from the original study acted as an expert reference. Spatial agreement between rater and expert masks was measured using the Dice Similarity Coefficient (DSC), and the influence of rater experience and individual dataset was examined using ANOVA. Each rater's masks were then used for spatial normalization of functional imaging data to the PAM50 template image. Using tissue regions defined in the template image, the gray matter-white matter signal contrast of the aligned functional data was used to evaluate the relative accuracy of the spatial normalization procedure across raters. Subject- and group-level analysis of activation during the left- and right-sided sensory stimuli were performed for each rater's co-registered data. Agreement with the expert's SC mask was associated with both rater experience level (F
(7,140) = 32.12, P < 2x10-16 , η² = 0.29) and dataset (F(20,140) = 20.58, P < 2x10-16 , η² = 0.53). Dataset variations may reflect image quality metrics: the ratio between the signal intensity of spinal cord voxels and surrounding cerebrospinal fluid was correlated with DSC results (p<0.001). As predicted, variability in the manually-drawn masks visibly influenced spatial normalization, and the GM:WM contrast in the registered data showed significant effects of rater and dataset (rater: F(8,160) = 23.57, P < 2x10-16 , η² = 0.24; dataset: F(20,160) = 22.00, P < 2x10-16 , η² = 0.56). These registration differences were propagated into activation mapping results, and subject-level activation maps showed rater-dependent agreement with the expert's maps. Although group-level activation maps differed between raters, no systematic bias was identified. While increasing consistency in manual contouring of spinal cord fMRI data could improve data co-registration and ultimately the inter-rater agreement in activation mapping, our results suggest that other improvements in image acquisition and post-processing may be more critical to address. [ABSTRACT FROM AUTHOR]- Published
- 2022
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17. Is fMRI “noise” really noise? Resting state nuisance regressors remove variance with network structure
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Bright, Molly G. and Murphy, Kevin
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- 2015
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18. Characterization of regional heterogeneity in cerebrovascular reactivity dynamics using novel hypocapnia task and BOLD fMRI
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Bright, Molly G., Bulte, Daniel P., Jezzard, Peter, and Duyn, Jeff H.
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- 2009
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19. Centering inclusivity in the design of online conferences - An OHBM-Open Science perspective
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Levitis, Elizabeth, van Praag, Cassandra D Gould, Gau, Rémi, Heunis, Stephan, DuPre, Elizabeth, Kiar, Gregory, Bottenhorn, Katherine L, Glatard, Tristan, Nikolaidis, Aki, Whitaker, Kirstie Jane, Mancini, Matteo, Niso, Guiomar, Afyouni, Soroosh, Alonso-Ortiz, Eva, Appelhoff, Stefan, Arnatkeviciute, Aurina, Atay, Selim Melvin, Auer, Tibor, Baracchini, Giulia, Bayer, Johanna M M, Beauvais, Michael J S, Bijsterbosch, Janine D, Bilgin, Isil P, Bollmann, Saskia, Bollmann, Steffen, Botvinik-Nezer, Rotem, Bright, Molly G, Calhoun, Vince D, Chen, Xiao, Chopra, Sidhant, Chuan-Peng, Hu, Close, Thomas G, Cookson, Savannah L, Craddock, R Cameron, De La Vega, Alejandro, De Leener, Benjamin, Demeter, Damion V, Di Maio, Paola, Dickie, Erin W, Eickhoff, Simon B, Esteban, Oscar, Finc, Karolina, Frigo, Matteo, Ganesan, Saampras, Ganz, Melanie, Garner, Kelly G, Garza-Villarreal, Eduardo A, Gonzalez-Escamilla, Gabriel, Goswami, Rohit, Griffiths, John D, Grootswagers, Tijl, Guay, Samuel, Guest, Olivia, Handwerker, Daniel A, Herholz, Peer, Heuer, Katja, Huijser, Dorien C, Iacovella, Vittorio, Joseph, Michael J E, Karakuzu, Agah, Keator, David B, Kobeleva, Xenia, Kumar, Manoj, Laird, Angela R, Larson-Prior, Linda J, Lautarescu, Alexandra, Lazari, Alberto, Legarreta, Jon Haitz, Lv, Jinglei, Mansour L, Sina, Meunier, David, Moraczewski, Dustin, Nandi, Tulika, Nastase, Samuel A, Nau, Matthias, Noble, Stephanie, Norgaard, Martin, Obungoloch, Johnes, Oostenveld, Robert, Orchard, Edwina R, Pinho, Ana Luísa, Poldrack, Russell A, Qiu, Anqi, Raamana, Pradeep Reddy, Rokem, Ariel, Rutherford, Saige, Sharan, Malvika, Shaw, Thomas B, Syeda, Warda T, Testerman, Meghan M, Toro, Roberto, Valk, Sofie L, Van Den Bossche, Sofie, Varoquaux, Gaël, Váša, František, Veldsman, Michele, Vohryzek, Jakub, Wagner, Adina S, Walsh, Reubs J, White, Tonya, Wong, Fu-Te, Xie, Xihe, Yan, Chao-Gan, Yang, Yu-Fang, Yee, Yohan, Zanitti, Gaston E, Van Gulick, Ana E, Duff, Eugene, and Maumet, Camille
- Abstract
As the global health crisis unfolded, many academic conferences moved online in 2020. This move has been hailed as a positive step towards inclusivity in its attenuation of economic, physical, and legal barriers and effectively enabled many individuals from groups that have traditionally been underrepresented to join and participate. A number of studies have outlined how moving online made it possible to gather a more global community and has increased opportunities for individuals with various constraints, e.g., caregiving responsibilities. Yet, the mere existence of online conferences is no guarantee that everyone can attend and participate meaningfully. In fact, many elements of an online conference are still significant barriers to truly diverse participation: the tools used can be inaccessible for some individuals; the scheduling choices can favour some geographical locations; the set-up of the conference can provide more visibility to well-established researchers and reduce opportunities for early-career researchers. While acknowledging the benefits of an online setting, especially for individuals who have traditionally been underrepresented or excluded, we recognize that fostering social justice requires inclusivity to actively be centered in every aspect of online conference design. Here, we draw from the literature and from our own experiences to identify practices that purposefully encourage a diverse community to attend, participate in, and lead online conferences. Reflecting on how to design more inclusive online events is especially important as multiple scientific organizations have announced that they will continue offering an online version of their event when in-person conferences can resume.
- Published
- 2021
20. Lag-Optimized Blood Oxygenation Level Dependent Cerebrovascular Reactivity Estimates Derived From Breathing Task Data Have a Stronger Relationship With Baseline Cerebral Blood Flow.
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Stickland, Rachael C., Zvolanek, Kristina M., Moia, Stefano, Caballero-Gaudes, César, and Bright, Molly G.
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CEREBRAL circulation ,RESPIRATION ,OXYGEN in the blood ,FUNCTIONAL magnetic resonance imaging ,HEMODYNAMICS - Abstract
Cerebrovascular reactivity (CVR), an important indicator of cerebrovascular health, is commonly studied with the Blood Oxygenation Level Dependent functional MRI (BOLD-fMRI) response to a vasoactive stimulus. Theoretical and empirical evidence suggests that baseline cerebral blood flow (CBF) modulates BOLD signal amplitude and may influence BOLD-CVR estimates. We address how acquisition and modeling choices affect the relationship between baseline cerebral blood flow (bCBF) and BOLD-CVR: whether BOLD-CVR is modeled with the inclusion of a breathing task, and whether BOLD-CVR amplitudes are optimized for hemodynamic lag effects. We assessed between-subject correlations of average GM values and within-subject spatial correlations across cortical regions. Our results suggest that a breathing task addition to a resting-state acquisition, alongside lag-optimization within BOLD-CVR modeling, can improve BOLD-CVR correlations with bCBF, both between- and within-subjects, likely because these CVR estimates are more physiologically accurate. We report positive correlations between bCBF and BOLD-CVR, both between- and within-subjects. The physiological explanation of this positive correlation is unclear; research with larger samples and tightly controlled vasoactive stimuli is needed. Insights into what drives variability in BOLD-CVR measurements and related measurements of cerebrovascular function are particularly relevant when interpreting results in populations with altered vascular and/or metabolic baselines or impaired cerebrovascular reserve. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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21. Reliable quantification of BOLD fMRI cerebrovascular reactivity despite poor breath-hold performance
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Bright, Molly G. and Murphy, Kevin
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- 2013
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22. The Effect of Basal Vasodilation on Hypercapnic and Hypocapnic Reactivity Measured using Magnetic Resonance Imaging
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Bright, Molly G, Donahue, Manus J, Duyn, Jeff H, Jezzard, Peter, and Bulte, Daniel P
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- 2011
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23. Machine Learning-Based Prediction of MRI-Induced Power Absorption in the Tissue in Patients With Simplified Deep Brain Stimulation Lead Models.
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Vu, Jasmine, Nguyen, Bach T., Bhusal, Bhumi, Baraboo, Justin, Rosenow, Joshua, Bagci, Ulas, Bright, Molly G., and Golestanirad, Laleh
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BRAIN stimulation ,DEEP brain stimulation ,MAGNETIC resonance imaging ,ELECTRONIC equipment ,ABSORPTION ,ALGORITHMS ,PREDICTION models - Abstract
Interaction of an active electronic implant such as a deep brain stimulation (DBS) system and magnetic resonance imaging (MRI) radiofrequency (RF) fields can induce excessive tissue heating, limiting MRI accessibility. Efforts to quantify RF heating mostly rely on electromagnetic (EM) simulations to assess individualized specific absorption rate (SAR), but such simulations require extensive computational resources. Here, we investigate if a predictive model using machine learning (ML) can predict the local SAR in the tissue around tips of implanted leads from the distribution of the tangential component of the MRI incident electric field, Etan. A dataset of 260 unique patient-derived and artificial DBS lead trajectories was constructed, and the 1 g-averaged SAR, 1 g SARmax, at the lead-tip during 1.5 T MRI was determined by EM simulations. Etan values along each lead's trajectory and the simulated SAR values were used to train and test the ML algorithm. The resulting predictions of the ML algorithm indicated that the distribution of Etan could effectively predict 1 g SARmax at the DBS lead-tip (R = 0.82). Our results indicate that ML has the potential to provide a fast method for predicting MR-induced power absorption in the tissue around tips of implanted leads such as those in active electronic medical devices. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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24. Cerebrovascular Reactivity Mapping Without Gas Challenges: A Methodological Guide.
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Pinto, Joana, Bright, Molly G., Bulte, Daniel P., and Figueiredo, Patrícia
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TRANSCRANIAL Doppler ultrasonography ,FUNCTIONAL magnetic resonance imaging ,BREATH holding ,CEREBRAL circulation ,FLOW velocity - Abstract
Cerebrovascular reactivity (CVR) is defined as the ability of vessels to alter their caliber in response to vasoactive factors, by means of dilating or constricting, in order to increase or decrease regional cerebral blood flow (CBF). Importantly, CVR may provide a sensitive biomarker for pathologies where vasculature is compromised. Furthermore, the spatiotemporal dynamics of CVR observed in healthy subjects, reflecting regional differences in cerebral vascular tone and response, may also be important in functional MRI studies based on neurovascular coupling mechanisms. Assessment of CVR is usually based on the use of a vasoactive stimulus combined with a CBF measurement technique. Although transcranial Doppler ultrasound has been frequently used to obtain global flow velocity measurements, MRI techniques are being increasingly employed for obtaining CBF maps. For the vasoactive stimulus, vasodilatory hypercapnia is usually induced through the manipulation of respiratory gases, including the inhalation of increased concentrations of carbon dioxide. However, most of these methods require an additional apparatus and complex setups, which not only may not be well-tolerated by some populations but are also not widely available. For these reasons, strategies based on voluntary breathing fluctuations without the need for external gas challenges have been proposed. These include the task-based methodologies of breath holding and paced deep breathing, as well as a new generation of methods based on spontaneous breathing fluctuations during resting-state. Despite the multitude of alternatives to gas challenges, existing literature lacks definitive conclusions regarding the best practices for the vasoactive modulation and associated analysis protocols. In this work, we perform an extensive review of CVR mapping techniques based on MRI and CO
2 variations without gas challenges, focusing on the methodological aspects of the breathing protocols and corresponding data analysis. Finally, we outline a set of practical guidelines based on generally accepted practices and available data, extending previous reports and encouraging the wider application of CVR mapping methodologies in both clinical and academic MRI settings. [ABSTRACT FROM AUTHOR]- Published
- 2021
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25. Arterial CO2 fluctuations modulate neuronal rhythmicity: Implications for MEG and fMRI studies of resting-state networks
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Driver, Ian D., Whittaker, Joseph R., Bright, Molly G., Muthukumaraswamy, Suresh D., and Murphy, Kevin
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magnetoencephalography ,Adult ,Male ,Neurons ,Brain Mapping ,physiological noise ,Behavioral/Cognitive ,Rest ,functional connectivity ,Brain ,hypercapnia ,Articles ,Carbon Dioxide ,Magnetic Resonance Imaging ,Oxygen ,Biological Clocks ,Image Processing, Computer-Assisted ,Linear Models ,RC0321 ,Humans ,Female ,Nerve Net ,cortical oscillations - Abstract
A fast emerging technique for studying human resting state networks (RSNs) is based on spontaneous temporal fluctuations in neuronal oscillatory power, as measured by magnetoencephalography. However, it has been demonstrated recently that this power is sensitive to modulations in arterial CO2 concentration. Arterial CO2 can be modulated by natural fluctuations in breathing pattern, as might typically occur during the acquisition of an RSN experiment. Here, we demonstrate for the first time the fine-scale dependence of neuronal oscillatory power on arterial CO2 concentration, showing that reductions in alpha, beta, and gamma power are observed with even very mild levels of hypercapnia (increased arterial CO2). We use a graded hypercapnia paradigm and participant feedback to rule out a sensory cause, suggesting a predominantly physiological origin. Furthermore, we demonstrate that natural fluctuations in arterial CO2, without administration of inspired CO2, are of a sufficient level to influence neuronal oscillatory power significantly in the delta-, alpha-, beta-, and gamma-frequency bands. A more thorough understanding of the relationship between physiological factors and cortical rhythmicity is required. In light of these findings, existing results, paradigms, and analysis techniques for the study of resting-state brain data should be revisited. SIGNIFICANCE STATEMENT In this study, we show for the first time that neuronal oscillatory power is intimately linked to arterial CO2 concentration down to the fine-scale modulations that occur during spontaneous breathing. We extend these results to demonstrate a correlation between neuronal oscillatory power and spontaneous arterial CO2 fluctuations in awake humans at rest. This work identifies a need for studies investigating resting-state networks in the human brain to measure and account for the impact of spontaneous changes in arterial CO2 on the neuronal signals of interest. Changes in breathing pattern that are time locked to task performance could also lead to confounding effects on neuronal oscillatory power when considering the electrophysiological response to functional stimulation.
- Published
- 2016
26. Cerebral Autoregulation Evidenced by Synchronized Low Frequency Oscillations in Blood Pressure and Resting-State fMRI.
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Whittaker, Joseph R., Driver, Ian D., Venzi, Marcello, Bright, Molly G., and Murphy, Kevin
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BLOOD pressure ,FUNCTIONAL magnetic resonance imaging ,BLOOD flow ,METABOLISM ,VASODILATORS - Abstract
Resting-state functional magnetic resonance imaging (rs-fMRI) is a widely used technique for mapping the brain's functional architecture, so delineating the main sources of variance comprising the signal is crucial. Low frequency oscillations (LFO) that are not of neural origin, but which are driven by mechanisms related to cerebral autoregulation (CA), are present in the blood-oxygenation-level-dependent (BOLD) signal within the rs-fMRI frequency band. In this study we use a MR compatible device (Caretaker, Biopac) to obtain a non-invasive estimate of beat-to-beat mean arterial pressure (MAP) fluctuations concurrently with rs-fMRI at 3T. Healthy adult subjects (n = 9; 5 male) completed two 20-min rs-fMRI scans. MAP fluctuations were decomposed into different frequency scales using a discrete wavelet transform, and oscillations at approximately 0.1 Hz show a high degree of spatially structured correlations with matched frequency fMRI fluctuations. On average across subjects, MAP fluctuations at this scale of the wavelet decomposition explain ∼2.2% of matched frequency fMRI signal variance. Additionally, a simultaneous multi-slice multi-echo acquisition was used to collect 10-min rs-fMRI at three echo times at 7T in a separate group of healthy adults (n = 5; 5 male). Multiple echo times were used to estimate the R
2 ∗ decay at every time point, and MAP was shown to strongly correlate with this signal, which suggests a purely BOLD (i.e., blood flow related) origin. This study demonstrates that there is a significant component of the BOLD signal that has a systemic physiological origin, and highlights the fact that not all localized BOLD signal changes necessarily reflect blood flow supporting local neural activity. Instead, these data show that a proportion of BOLD signal fluctuations in rs-fMRI are due to localized control of blood flow that is independent of local neural activity, most likely reflecting more general systemic autoregulatory processes. Thus, fMRI is a promising tool for studying flow changes associated with cerebral autoregulation with high spatial resolution. [ABSTRACT FROM AUTHOR]- Published
- 2019
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27. Corrigendum: Cerebral Autoregulation Evidenced by Synchronized Low Frequency Oscillations in Blood Pressure and Resting-State fMRI.
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Whittaker, Joseph R., Driver, Ian D., Venzi, Marcello, Bright, Molly G., and Murphy, Kevin
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BLOOD pressure ,CEREBRAL circulation ,CAROTID artery diseases - Abstract
Keywords: cerebral autoregulation; resting-state fMRI; blood pressure; cerebral physiology; LFO; BOLD; CBF EN cerebral autoregulation resting-state fMRI blood pressure cerebral physiology LFO BOLD CBF 1 3 3 06/27/20 20200624 NES 200624 In the original article, there was an error. In the article it is implied that MAP precedes fMRI by approximately 5.5 s, whereas in fact the fMRI signal precedes the MAP signal. Thus, this is consistent with the fMRI literature showing low frequency fMRI signals of systemic origin that are delayed in white matter, as blood arrival time is extended with respect to gray matter (van Gelderen et al., [15]).". [Extracted from the article]
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- 2020
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28. Cleaning up the fMRI time series: Mitigating noise with advanced acquisition and correction strategies
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Bright, Molly G. and Murphy, Kevin
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- 2017
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29. Arterial CO2 Fluctuations Modulate Neuronal Rhythmicity: Implications for MEG and fMRI Studies of Resting-State Networks.
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Driver, Ian D., Whittaker, Joseph R., Bright, Molly G., Muthukumaraswamy, Suresh D., and Murphy, Kevin
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HYPERCAPNIA ,CARBON dioxide in the blood ,ARTERIES ,ALPHA rhythm ,BETA rhythm ,NEURONS ,BRAIN research - Abstract
The article focuses on a demonstration of fine-scale dependence of oscillatory power of neurons on arterial carbon dioxide concentrations and the impact of alpha, beta, and gamma power with mild levels of hypercapnia. It states a graded hypercapnia paradigm and feedback by participants was used to rule out sensory causes and demonstrated natural changes in arterial carbon dioxide was sufficient to influence neuronal oscillatory power. It suggests resting-state brain research should be revisited.
- Published
- 2016
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30. Macrovascular blood flow and microvascular cerebrovascular reactivity are regionally coupled in adolescence.
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Zvolanek KM, Moore JE, Jarvis K, Moum SJ, and Bright MG
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Cerebrovascular imaging assessments are particularly challenging in adolescent cohorts, where not all modalities are appropriate, and rapid brain maturation alters hemodynamics at both macro- and microvascular scales. In a preliminary sample of healthy adolescents (n=12, 8-25 years), we investigated relationships between 4D flow MRI-derived blood velocity and blood flow in bilateral anterior, middle, and posterior cerebral arteries and BOLD cerebrovascular reactivity in associated vascular territories. As hypothesized, higher velocities in large arteries are associated with an earlier response to a vasodilatory stimulus (cerebrovascular reactivity delay) in the downstream territory. Higher blood flow through these arteries is associated with a larger BOLD response to a vasodilatory stimulus (cerebrovascular reactivity amplitude) in the associated territory. These trends are consistent in a case study of adult moyamoya disease. In our small adolescent cohort, macrovascular-microvascular relationships for velocity/delay and flow/CVR change with age, though underlying mechanisms are unclear. Our work emphasizes the need to better characterize this key stage of human brain development, when cerebrovascular hemodynamics are changing, and standard imaging methods offer limited insight into these processes. We provide important normative data for future comparisons in pathology, where combining macro- and microvascular assessments may better help us prevent, stratify, and treat cerebrovascular disease.
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- 2024
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31. Simultaneous cortical, subcortical, and brainstem mapping of sensory activation.
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Reddy NA, Clements RG, Brooks JCW, and Bright MG
- Abstract
Non-painful tactile sensory stimuli are processed in the cortex, subcortex, and brainstem. Recent functional magnetic resonance imaging (fMRI) studies have highlighted the value of whole-brain, systems-level investigation for examining pain processing. However, whole-brain fMRI studies are uncommon, in part due to challenges with signal to noise when studying the brainstem. Furthermore, the differentiation of small sensory brainstem structures such as the cuneate and gracile nuclei necessitates high resolution imaging. To address this gap in systems-level sensory investigation, we employed a whole-brain, multi-echo fMRI acquisition at 3T with multi-echo independent component analysis (ME-ICA) denoising and brainstem-specific modeling to enable detection of activation across the entire sensory system. In healthy participants, we examined patterns of activity in response to non-painful brushing of the right hand, left hand, and right foot, and found the expected lateralization, with distinct cortical and subcortical responses for upper and lower limb stimulation. At the brainstem level, we were able to differentiate the small, adjacent cuneate and gracile nuclei, corresponding to hand and foot stimulation respectively. Our findings demonstrate that simultaneous cortical, subcortical, and brainstem mapping at 3T could be a key tool to understand the sensory system in both healthy individuals and clinical cohorts with sensory deficits., Competing Interests: Declaration of competing interest The authors declare no competing financial interests.
- Published
- 2024
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32. MRI mapping of hemodynamics in the human spinal cord.
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Hemmerling KJ, Hoggarth MA, Sandhu MS, Parrish TB, and Bright MG
- Abstract
Impaired spinal cord vascular function contributes to numerous neurological pathologies, making it important to be able to noninvasively characterize these changes. Here, we propose a functional magnetic resonance imaging (fMRI)-based method to map spinal cord vascular reactivity (SCVR). We used a hypercapnic breath-holding task, monitored with end-tidal CO
2 (PET CO2 ), to evoke a systemic vasodilatory response during concurrent blood oxygenation level-dependent (BOLD) fMRI. SCVR amplitude and hemodynamic delay were mapped at the group level in 27 healthy participants as proof-of-concept of the approach, and then in two highly-sampled participants to probe feasibility/stability of individual SCVR mapping. Across the group and the highly-sampled individuals, a strong ventral SCVR amplitude was initially observed without accounting for local regional variation in the timing of the vasodilatory response. Shifted breathing traces (PET CO2 ) were used to account for temporal differences in the vasodilatory response across the spinal cord, producing maps of SCVR delay. These delay maps reveal an earlier ventral and later dorsal response and demonstrate distinct gray matter regions concordant with territories of arterial supply. The SCVR fMRI methods described here enable robust mapping of spatiotemporal hemodynamic properties of the human spinal cord. This noninvasive approach has exciting potential to provide early insight into pathology-driven vascular changes in the cord, which may precede and predict future irreversible tissue damage and guide the treatment of several neurological pathologies involving the spine.- Published
- 2024
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33. Denoising task-correlated head motion from motor-task fMRI data with multi-echo ICA.
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Reddy NA, Zvolanek KM, Moia S, Caballero-Gaudes C, and Bright MG
- Abstract
Motor-task functional magnetic resonance imaging (fMRI) is crucial in the study of several clinical conditions, including stroke and Parkinson's disease. However, motor-task fMRI is complicated by task-correlated head motion, which can be magnified in clinical populations and confounds motor activation results. One method that may mitigate this issue is multi-echo independent component analysis (ME-ICA), which has been shown to separate the effects of head motion from the desired BOLD signal but has not been tested in motor-task datasets with high amounts of motion. In this study, we collected an fMRI dataset from a healthy population who performed a hand grasp task with and without task-correlated amplified head motion to simulate a motor-impaired population. We analyzed these data using three models: single-echo (SE), multi-echo optimally combined (ME-OC), and ME-ICA. We compared the models' performance in mitigating the effects of head motion on the subject level and group level. On the subject level, ME-ICA better dissociated the effects of head motion from the BOLD signal and reduced noise. Both ME models led to increased t-statistics in brain motor regions. In scans with high levels of motion, ME-ICA additionally mitigated artifacts and increased stability of beta coefficient estimates, compared to SE. On the group level, all three models produced activation clusters in expected motor areas in scans with both low and high motion, indicating that group-level averaging may also sufficiently resolve motion artifacts that vary by subject. These findings demonstrate that ME-ICA is a useful tool for subject-level analysis of motor-task data with high levels of task-correlated head motion. The improvements afforded by ME-ICA are critical to improve reliability of subject-level activation maps for clinical populations in which group-level analysis may not be feasible or appropriate, for example in a chronic stroke cohort with varying stroke location and degree of tissue damage., Competing Interests: Declaration of competing interest The authors declare no competing financial interests.
- Published
- 2023
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34. Spatial distribution of hand-grasp motor task activity in spinal cord functional magnetic resonance imaging.
- Author
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Hemmerling KJ, Hoggarth MA, Sandhu MS, Parrish TB, and Bright MG
- Abstract
Upper extremity motor paradigms during spinal cord functional magnetic resonance imaging (fMRI) can provide insight into the functional organization of the cord. Hand-grasping is an important daily function with clinical significance, but previous studies of similar squeezing movements have not reported consistent areas of activity and are limited by sample size and simplistic analysis methods. Here, we study spinal cord fMRI activation using a unimanual isometric hand-grasping task that is calibrated to participant maximum voluntary contraction (MVC). Two task modeling methods were considered: (1) a task regressor derived from an idealized block design (Ideal) and (2) a task regressor based on the recorded force trace normalized to individual MVC (%MVC). Across these two methods, group motor activity was highly lateralized to the hemicord ipsilateral to the side of the task. Activation spanned C5-C8 and was primarily localized to the C7 spinal cord segment. Specific differences in spatial distribution are also observed, such as an increase in C8 and dorsal cord activity when using the %MVC regressor. Furthermore, we explored the impact of data quantity and spatial smoothing on sensitivity to hand-grasp motor task activation. This analysis shows a large increase in number of active voxels associated with the number of fMRI runs, sample size, and spatial smoothing, demonstrating the impact of experimental design choices on motor activation.
- Published
- 2023
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35. A visualization tool for assessment of spinal cord functional magnetic resonance imaging data quality.
- Author
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Hemmerling KJ and Bright MG
- Subjects
- Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Neuroimaging, Data Accuracy, Spinal Cord diagnostic imaging
- Abstract
Functional magnetic resonance imaging (fMRI) is an extensively used neuroimaging technique to non-invasively detect neural activity. Data quality is highly variable, and fMRI analysis typically consists of a number of complex processing steps. It is crucial to visually assess images throughout analysis to ensure that data quality at each step is satisfactory. For fMRI analysis of the brain, there is a simple tool to visualize four-dimensional data on a two-dimensional plot for qualitative analysis. Despite the practicality of this method, it cannot be directly applied to fMRI data of the spinal cord, and a comparable approach does not exist for spinal cord fMRI analysis. The additional challenges encountered in spinal cord imaging, including the small size of the cord and the influence of physiological noise sources, drive the importance of developing a similar visualization technique for spinal cord fMRI. Here, we introduce a highly versatile image analysis tool to visualize spinal cord fMRI data as a simple heatmap and to co-visualize relevant traces such as physiological or motion timeseries. We present multiple variations of the plot, data features that can be identified with the heatmap, and examples of the useful qualitative analyses that can be performed using this method. The spinal cord plot can be easily integrated into an fMRI analysis pipeline and can streamline visual inspection and qualitative analysis of functional imaging data.Clinical Relevance- Implementation of this data visualization method is a simple addition to spinal cord fMRI analysis that could be used to identify normal vs. abnormal signal variation in pathologies that impact the cord, such as spinal cord injury or multiple sclerosis.
- Published
- 2021
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36. Centering inclusivity in the design of online conferences-An OHBM-Open Science perspective.
- Author
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Levitis E, van Praag CDG, Gau R, Heunis S, DuPre E, Kiar G, Bottenhorn KL, Glatard T, Nikolaidis A, Whitaker KJ, Mancini M, Niso G, Afyouni S, Alonso-Ortiz E, Appelhoff S, Arnatkeviciute A, Atay SM, Auer T, Baracchini G, Bayer JMM, Beauvais MJS, Bijsterbosch JD, Bilgin IP, Bollmann S, Bollmann S, Botvinik-Nezer R, Bright MG, Calhoun VD, Chen X, Chopra S, Chuan-Peng H, Close TG, Cookson SL, Craddock RC, De La Vega A, De Leener B, Demeter DV, Di Maio P, Dickie EW, Eickhoff SB, Esteban O, Finc K, Frigo M, Ganesan S, Ganz M, Garner KG, Garza-Villarreal EA, Gonzalez-Escamilla G, Goswami R, Griffiths JD, Grootswagers T, Guay S, Guest O, Handwerker DA, Herholz P, Heuer K, Huijser DC, Iacovella V, Joseph MJE, Karakuzu A, Keator DB, Kobeleva X, Kumar M, Laird AR, Larson-Prior LJ, Lautarescu A, Lazari A, Legarreta JH, Li XY, Lv J, Mansour L S, Meunier D, Moraczewski D, Nandi T, Nastase SA, Nau M, Noble S, Norgaard M, Obungoloch J, Oostenveld R, Orchard ER, Pinho AL, Poldrack RA, Qiu A, Raamana PR, Rokem A, Rutherford S, Sharan M, Shaw TB, Syeda WT, Testerman MM, Toro R, Valk SL, Van Den Bossche S, Varoquaux G, Váša F, Veldsman M, Vohryzek J, Wagner AS, Walsh RJ, White T, Wong FT, Xie X, Yan CG, Yang YF, Yee Y, Zanitti GE, Van Gulick AE, Duff E, and Maumet C
- Abstract
As the global health crisis unfolded, many academic conferences moved online in 2020. This move has been hailed as a positive step towards inclusivity in its attenuation of economic, physical, and legal barriers and effectively enabled many individuals from groups that have traditionally been underrepresented to join and participate. A number of studies have outlined how moving online made it possible to gather a more global community and has increased opportunities for individuals with various constraints, e.g., caregiving responsibilities. Yet, the mere existence of online conferences is no guarantee that everyone can attend and participate meaningfully. In fact, many elements of an online conference are still significant barriers to truly diverse participation: the tools used can be inaccessible for some individuals; the scheduling choices can favour some geographical locations; the set-up of the conference can provide more visibility to well-established researchers and reduce opportunities for early-career researchers. While acknowledging the benefits of an online setting, especially for individuals who have traditionally been underrepresented or excluded, we recognize that fostering social justice requires inclusivity to actively be centered in every aspect of online conference design. Here, we draw from the literature and from our own experiences to identify practices that purposefully encourage a diverse community to attend, participate in, and lead online conferences. Reflecting on how to design more inclusive online events is especially important as multiple scientific organizations have announced that they will continue offering an online version of their event when in-person conferences can resume., (© The Author(s) 2021. Published by Oxford University Press on behalf of GigaScience. 2021.)
- Published
- 2021
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37. Voxelwise optimization of hemodynamic lags to improve regional CVR estimates in breath-hold fMRI.
- Author
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Moia S, Stickland RC, Ayyagari A, Termenon M, Caballero-Gaudes C, and Bright MG
- Subjects
- Brain diagnostic imaging, Hemodynamics, Oxygen, Cerebrovascular Circulation, Magnetic Resonance Imaging
- Abstract
Cerebrovascular Reactivity (CVR), the responsiveness of blood vessels to a vasodilatory stimulus, is an important indicator of cerebrovascular health. Assessing CVR with fMRI, we can measure the change in the Blood Oxygen Level Dependent (BOLD) response induced by a change in CO2 pressure (%BOLD/mmHg). However, there exists a temporal offset between the recorded CO2 pressure and the local BOLD response, due to both measurement and physiological delays. If this offset is not corrected for, voxel-wise CVR values will not be accurate. In this paper, we propose a framework for mapping hemodynamic lag in breath-hold fMRI data. As breath-hold tasks drive task-correlated head motion artifacts in BOLD fMRI data, our framework for lag estimation fits a model that includes polynomial terms and head motion parameters, as well as a shifted variant of the CO2 regressor (±9 s in 0.3 s increments), and the hemodynamic lag at each voxel is the shift producing the maximum total model R2 within physiological constraints. This approach is evaluated in 8 subjects with multi-echo fMRI data, resulting in robust maps of hemodynamic delay that show consistent regional variation across subjects, and improved contrast-to-noise compared to methods where motion regression is ignored or performed earlier in preprocessing.Clinical Relevance- We map hemodynamic lag using breathhold fMRI, providing insight into vascular transit times and improving the regional accuracy of cerebrovascular reactivity measurements.
- Published
- 2020
- Full Text
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