Schedule of Events | Symposia

Sketchpad Series

Subcortical dynamics during failures in maintaining alertness after sleep restriction in the human brain.

Poster Session A - Saturday, March 29, 2025, 3:00 – 5:00 pm EDT, Back Bay Ballroom/Republic Ballroom
Also presenting in Data Blitz Session 2 - Saturday, March 29, 2025, 10:30 am – 12:00 pm EDT, Independence Ballroom.

Ewa Beldzik^1,2 (ewa.beldzik@gmail.com), Daniel Gomez², Nicholas Cicero^1,2,3, Zinong Yang^1,3, Juan Eugenio Iglesias^1,2, Brian Edlow^2,4, Laura Lewis^1,2,3; ¹Massachusetts Institute of Technology, ²Massachusetts General Hospital, ³Boston University, ⁴Harvard Medical School

Sleep restriction can severely impair alertness, resulting in delayed responses, omissions, or microsleeps. The neural dynamics underlying these drowsy periods and subsequent recovery to alertness are not well understood. Previous fMRI studies have focused on cortical and thalamic regions, which likely reflect downstream effects of dysregulated arousal mechanisms originating in the brainstem and hypothalamus, as shown in animal research. However, high-resolution imaging of these structures in humans is limited due to their small size and deep location. This study aimed to overcome these challenges using ultra-high-field (7T) fMRI to measure activity in brain regions critical for sleep-wake regulation during a simple attention task (psychomotor vigilance task) in sleep-restricted subjects (n=25). We applied advanced subcortical segmentation tools to analyze hemodynamic activity linked to the first omission trial (entering drowsiness) or the first alert trial after an omission (regaining alertness), across all nuclei of the ascending arousal network (AAN). We found that at the onset of drowsiness, activity decreased across all AAN regions, except for the tuberomammillary nucleus, which increased. Regaining alertness was marked by a strong increase in AAN activity, except in the hypothalamic preoptic area, which decreased, consistent with its sleep-promoting function. These patterns were influenced by the duration of the drowsiness period. Further, distinct temporal characteristics (e.g., number, latency, and width of peaks/troughs) in the hemodynamic activity across AAN regions suggested local neuromodulatory effects on the fMRI signal. Our findings shed light on the complex interactions between subcortical circuits that mediate attentional lapses after sleep restriction.

Topic Area: ATTENTION: Other