# Ascending Arousal Network Control of Sleep-Wake Structure in Humans Using Simultaneous EEG and High-Resolution fMRI

> **NIH NIH F31** · BOSTON UNIVERSITY MEDICAL CAMPUS · 2024 · $48,974

## Abstract

PROJECT SUMMARY
 Sleep is an important behavior for humans and many other species, impacting mood, cognition, and
waste clearance in the brain. Receiving sufficient sleep requires the brain to undergo widespread changes in
stereotyped sleep cycles, going between rapid eye movement (REM) sleep and non-REM (NREM) sleep. This
important sleep structure is established by several deep brain regions, together known as the ascending
arousal network (AAN). Regions within the AAN connect to each other and much of the brain, releasing
neuromodulators diffusely throughout. Although research in rodents has separately shown that regions of the
AAN regulate transitions between sleep-wake states, how this network modulates arousal state in humans and
how these regions coordinate to do so remains unknown. The small size of the regions of the AAN and other
technical limitations have limited direct measurement of the human AAN; however, advancements in magnetic
resonance imaging (MRI) at ultra-high magnetic fields has improved the spatiotemporal resolution of functional
MRI (fMRI), positioning us to study human AAN control of arousal states.
 The ultimate objective of this study is to identify the functional role of the human AAN in supporting arousal
states, through maintenance of arousal states and transitions between sleep-wake states. To do so, I will employ
simultaneous electroencephalography (EEG) and functional MRI while human subjects sleep in the MRI scanner
for a four-hour scan. We will bring in subjects around their typical bedtime and during the resting scan they will
be instructed to close their eyes while we track behavioral responsivity and electrophysiological arousal state.
To improve the spatial resolution of our fMRI scans, we have created a high spatial resolution functional
sequence which more closely matches the smallest cross-sectional dimensions of regions of the AAN. In aim 1,
our goal is to identify the response profile and intrinsic dynamics of the AAN during prolonged periods of wake
and sleep, as well as at transitions between states. In aim 2, our goal is to identify the impact of sleep on sensory
processing and how the regions of the AAN modulate the impact of sensory stimuli on arousal state. To assess
this, the same experimental setup will be used as in aim 1 while presenting a high-intensity visual stimulus to
probe sensory processing across arousal states. From aim 2 we will be able to understand stimulus-locked
responses of the AAN and visual areas during sleep-wake states, as well as assess how activity in these regions
may maintain or change arousal states.
 Throughout this project, Mr. Cicero will be sponsored and mentored by several personnel with expertise
in simultaneous EEG-fMRI, brainstem circuits, thalamocortical neural dynamics, and ultra-high field MRI. The
research training will be taking place across Boston University’s Graduate Program in Neuroscience.
Massachusetts Institute of Technology’s Research Laboratory of E...

## Key facts

- **NIH application ID:** 10996254
- **Project number:** 1F31NS139696-01
- **Recipient organization:** BOSTON UNIVERSITY MEDICAL CAMPUS
- **Principal Investigator:** Nicholas Gregory Cicero
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $48,974
- **Award type:** 1
- **Project period:** 2025-01-01 → 2028-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10996254

## Citation

> US National Institutes of Health, RePORTER application 10996254, Ascending Arousal Network Control of Sleep-Wake Structure in Humans Using Simultaneous EEG and High-Resolution fMRI (1F31NS139696-01). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/10996254. Licensed CC0.

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