Guest Presenter: Dr.Laura Lewis (Assistant Professor in Biomedical Engineering at Boston University)

Talk Title: Imaging Neural, Hemodynamic, and Cerebrospinal Fluid Dynamics in the Sleeping Brain.

Abstract: Sleep is essential for cognition and maintenance of healthy brain function. Sleep changes diverse aspects of brain function, from behavioral states to electrophysiological dynamics and waste clearance properties. Our research uses fast multimodal neuroimaging to understand the neural circuits controlling sleep and the consequences of sleep for brain physiology. We found that fast fMRI can track hemodynamics on subsecond timescales, and used simultaneous fast fMRI and EEG to measure fluid and neural dynamics in the human brain. We found a coherent pattern of coupled electrophysiological, hemodynamic, and cerebrospinal fluid (CSF) dynamics that appears during non-rapid eye movement sleep. Our results demonstrate that the sleeping brain exhibits waves of CSF flow on a macroscopic scale, and suggests a neural mechanism that can regulate CSF flow. Next, using fast fMRI at ultra-high field (7 Tesla), we tracked subsecond dynamics throughout thalamocortical networks across transitions between sleep and wakefulness. We identified a temporal sequence of activity across individual thalamic nuclei that appears at the moment of awakening from sleep and predicts subsequent behavioral states. Together, these studies develop multimodal approaches for imaging the human brain at fast timescales, and identify neurophysiological dynamics unique to the sleeping brain.