Task-related BOLD responses and resting-state functional connectivity during physiological clamping of end-tidal CO 2

Madjar, C., Gauthier, C. J., Bellec, P., Birn, R. M., Brooks, J. C.W. ORCID: https://orcid.org/0000-0003-3335-6209 and Hoge, R. D. (2012) Task-related BOLD responses and resting-state functional connectivity during physiological clamping of end-tidal CO 2. NeuroImage, 61 (1). pp. 41-49. ISSN 1053-8119

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Abstract

Carbon dioxide (CO 2), a potent vasodilator, is known to have a significant impact on the blood-oxygen level dependent (BOLD) signal. With the growing interest in studying synchronized BOLD fluctuations during the resting state, the extent to which the apparent synchrony is due to variations in the end-tidal pressure of CO 2 (PETCO 2) is an important consideration. CO 2-related fluctuations in BOLD signal may also represent a potential confound when studying task-related responses, especially if breathing depth and rate are affected by the task. While previous studies of the above issues have explored retrospective correction of BOLD fluctuations related to arterial PCO 2, here we demonstrate an alternative approach based on physiological clamping of the arterial CO 2 level to a near-constant value. We present data comparing resting-state functional connectivity within the default-mode-network (DMN), as well as task-related BOLD responses, acquired in two conditions in each subject: 1) while subject's PETCO 2 was allowed to vary spontaneously; and 2) while controlling subject's PETCO 2 within a narrow range. Strong task-related responses and areas of maximal signal correlation in the DMN were not significantly altered by suppressing fluctuations in PETCO 2. Controlling PETCO 2 did, however, improve the performance of retrospective physiological noise correction techniques, allowing detection of additional regions of task-related response and resting-state connectivity in highly vascularized regions such as occipital cortex. While these results serve to further rule out systemic physiological fluctuations as a significant source of apparent resting-state network connectivity, they also demonstrate that fluctuations in arterial CO 2 are one of the factors limiting sensitivity in task-based and resting-state fMRI, particularly in regions of high vascular density. This must be considered when comparing subject groups who might exhibit differences in respiratory physiology or breathing patterns.

Item Type: Article
Additional Information: Funding Information: We thank Olivia Bibollet-Bahena, Carollyn Hurst and André Cyr for help with data acquisition, Julien Cohen-Adad for helpful discussions. This work was supported by the Quebec Bio-Imaging Network (pilot project) , Canadian Institutes for Health Research ( MOP 84378 ), Canadian Foundation for Innovation (Leaders Opportunity Fund 17380 ) and the Natural Sciences and Engineering Research Council of Canada (Electrical and Computer Engineering 1510 ).
Uncontrolled Keywords: bold fmri,default-mode-network,end-tidal co fluctuations,physiological noise,resting-state functional connectivity,task-related response,neurology,cognitive neuroscience ,/dk/atira/pure/subjectarea/asjc/2800/2808
Faculty \ School: Faculty of Social Sciences > School of Psychology
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Depositing User: LivePure Connector
Date Deposited: 07 Sep 2022 11:31
Last Modified: 23 Sep 2022 02:44
URI: https://ueaeprints.uea.ac.uk/id/eprint/87800
DOI: 10.1016/j.neuroimage.2012.02.080

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