Name: Sakshi Dhawan

Ph.D. Dissertation Proposal Meeting

Date: Tuesday, December 17, 2024

Time: 10:00 am - 11:30 am

Location: Virtual (http://gatech.zoom.us/my/eschu)

Dissertation Chairs/Advisor:

Eric Schumacher, Ph.D. (Georgia Tech)

Dissertation Committee Members:

Mark Wheeler, Ph.D. (Georgia Tech)

Thackery Brown, Ph.D. (Georgia Tech)

Shella Keilholz, Ph.D. (Emory University/ Georgia Institute of Technology)

Audrey Duarte, Ph.D. (University of Texas at Austin, Texas)

 Title: The effect of working memory load and sleep quality on dynamic network connectivity during rest and n-back task performance 

Abstract: Quasi-periodic patterns (QPPs) are recurrent low-frequency fluctuations that play an important role in the functional connectivity between Default Mode (DMN) and Task Positive Networks (TPN). Research indicates that attentional focus and arousal fluctuations impact QPPs during rest and tasks (Abbas et al., 2019a; Abbas et al., 2019b). Abbas and colleagues (2019a) found that the anti-correlation between DMN-TPN was stronger in the task (0-back and 2-back combined) as compared to the rest condition. Previous research has shown that an increase in working memory load affects performance and the functional activations in the brain (Miri Ashtiani & Daliri, 2023; Jonides et al., 1997; Owen et al., 2005) so it is unknown from Abbas and colleagues (2019a) if QPPs are affected differently at different levels of n-back. Neurocognitive performance is also impacted by the individual’s sleep duration with daytime sleepiness reducing DMN connectivity in young adults (Ward et al., 2013), thereby producing altered connectivity between the DMN and the TPN. Past sleep behaviors including experimentally induced, acute sleep deprivation (De Havas, Parimal, Soon, & Chee, 2012; Gujar, Yoo, Hu, & Walker, 2010; Yeo, Tandi, & Chee, 2015) and habitual sleep duration estimated from wrist actigraphy (Khalsa et al., 2016) have also been linked with reductions in the functional connectivity of DMN during wakefulness. Since QPP is affected by task performance, arousal, and sleep quality, we are investigating the interaction among these factors at different levels of n-back and sleep quality. We would like to address the limitations of Abbas et al. (2019a) and use separate 0-back and 2-back tasks to examine the differences between them. Participants’ sleep quality and duration were measured for three days before scanning. During scanning, they performed rest, 0-back, and 2-back blocks. We expect to see differences in the QPP patterns of all three conditions and between sleep groups. Therefore, this study aims to demonstrate the relationship between QPPs and brain networks and how this relationship changes with arousal and relates to task performance.