Investigating the role of brain arousal fluctuations in resting-state functional magnetic resonance imaging
- Gu, Yameng
- [University Park, Pennsylvania] : Pennsylvania State University, 2021.
- Physical Description:
- 1 electronic document
- Additional Creators:
- Drewe, Patrick
- Restrictions on Access:
- Restricted (PSU Only).
- Resting-state functional magnetic resonance imaging (rsfMRI) has been widely used to probe spontaneous neural activity and study brain organization. RsfMRI signals provide useful information for detecting brain dysfunction in neurologic and psychiatric diseases and shed light on brain organization. RsfMRI signals and rsfMRI-derived metrics showed significant differences under different brain arousal states. Even within a long-standing rsfMRI scanning session, it would be very difficult for subjects to keep a constant arousal or vigilance level. The fluctuation in arousal and vigilance is expected to affect rsfMRI signals and thus the rsfMRI-derived quantification of brain connectivity and dynamics. It is thus important to quantify and control the effects of brain arousal changes on rsfMRI signals. The study of such arousal-related rsfMRI change may also provide a good opportunity to understand the neural mechanisms underlying brain arousal regulations. In this dissertation, we first examined the effects of brain arousal modulations on the rsfMRI-derived measurement of functional connectivity. We found that the arousal-related rsfMRI changes lead to systematic changes of functional connectivity, i.e., increases in the short-range connectivity whereas decreases in the long-range ones, which have been misinterpreted as the head motion effect. Next, we showed the arousal-related rsfMRI changes take a specific spatiotemporal pattern of the fMRI cascade. More importantly, this cascade event of >10s in duration is accompanied by strong modulation in various neural and physiological signals, leading to strong correlations with rsfMRI and among themselves. Lastly, we inspected the detailed spatiotemporal dynamics of arousal-related fMRI changes with a high-quality data set and found that they often take the form of propagating waves in the cortex along the gradient of the cortical hierarchy. We further prove the neural origin of such rsfMRI propagations by showing similar activity in monkey electrophysiology free of hemodynamic confounding. Overall, this dissertation work combined multimodal neuroimage data to map the spatiotemporal dynamics of arousal-related fMRI changes,and their potential effects on rsfMRI-derived measurements of brain connectivity and dynamics. It highlights the importance of proper interpretation and control of arousal-related fMRI changes, and also provides novel insight into the large-scale brain dynamics related to arousal modulations.
- Other Subject(s):
- Dissertation Note:
- Ph.D. Pennsylvania State University 2021.
- Technical Details:
- The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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