PhD Proposal by Nmachi Anumba

Event Details
  • Date/Time:
    • Wednesday April 20, 2022
      12:30 pm - 2:00 pm
  • Location: HSRB E182 (Emory)
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Summary Sentence: Studying the effects of noradrenergic neuromodulation on the BOLD global signal and quasi-periodic patterns in rat rs-fMRI

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Nmachi Anumba
BME PhD Proposal Presentation

Time: 12:30 PM - 2:00 PM
Location / Meeting Link: HSRB E182 (Emory) | (Meeting ID: 951 4911 2169)

Committee Members:
Shella Keilholz, Ph.D. (Advisor) David Weinshenker, Ph.D. Erin Buckley, Ph.D. Garrett Stanley, Ph.D. Candace Fleischer, Ph.D.

Title: Studying the effects of noradrenergic neuromodulation on the BOLD global signal and quasi-periodic patterns in rat rs-fMRI

Abstract: Throughout the years, the field of neuroscience has learned a lot about how specific parts of the brain correspond to specific actions and behaviors. More recently, there has been an increase in studies of at-rest brain activity, showcasing dynamics and networks that underlie important brain functions. While at rest, brain activity is subject to constant neuromodulatory input from brainstem nuclei. In particular, activity of the locus coeruleus (LC), a brainstem nucleus responsible for the release of norepinephrine and known to play a significant role in arousal, has been shown to affect resting-state brain activity. Resting-state fMRI (rs-fMRI), performed when the subject is awake but not involved in a task, provides us with a unique opportunity to study the brain’s intrinsic functionality through the blood oxygenation level dependent (BOLD) signal. Developments in rs-fMRI studies have shown that brain activity is not exclusively localized to specific areas, but that large-scale coordinated activity across brain structures is also present. Two prominent examples of these spatiotemporal patterns are the BOLD global signal and quasi-periodic patterns (QPPs). The global signal is defined as the averaged activity of the brain during a scan and its use as a nuisance regressor has been a contentious topic for years. QPPs are widespread waves of brain activity that are observed at rest and contribute to whole-brain functional connectivity. Speculation that QPPs may originate from the activity of brainstem nuclei, in addition to findings that link the global signal to levels of arousal, lead us to believe that the widespread nature of LC influence could have a significant effect on these two signals. For my Ph.D. thesis, I am proposing to use optogenetic-fMRI to study the direct effects of LC activity on the BOLD global signal and QPPs in rats. I plan to do this by first identifying a global signal component that is associated with brain activity and consequently could be affected by LC neuromodulation (Aim 1). Secondly, I plan to use optogenetic-fMRI to stimulate the LC at different frequencies and study how these varying levels of LC activity affect both the global signal and QPPs (Aim 2). This work is critical for working towards a complete understanding of these resting-state signals and how they reflect the underlying functionality of the brain.

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Phd proposal
  • Created By: Tatianna Richardson
  • Workflow Status: Published
  • Created On: Apr 7, 2022 - 10:58am
  • Last Updated: Apr 7, 2022 - 10:58am