The nightlife of the brain
Professor of Glial Cell Biology
Center for Basic and Translational Neuroscience
University of Copenhagen
Dean’s Professor and Co-Director of the Center for Translational Neuromedicine
University of Rochester Medical Center
The concerted release of neuromodulators, including norepinephrine, acetylcholine, histamine, dopamine, and orexin mediates arousal. All of these neuromodulators individually alter the membrane properties, spiking activity, and intracellular signaling pathways of subpopulations of neurons and glia, but how they implement the striking stereotypic patterns of EEG activity characterizing wakefulness versus sleep is not understood. We have in recent work found astrocytes play an unexpected important role in modulating the state of brain activity. In response to neuromodulators and in particular, norepinephrine, astrocytes control the extracellular ion concentrations. In turn, the changes in extracellular K+, Ca2+, and Mg2+ appears to play a crucial role in shaping the changes in EEG activity that characterize the sleep-wake cycle. Concurrently, astrocytes control the glymphatic clearance system, which is primarily active during sleep. The seminar will discuss the interconnections between astrocytic regulation of ion and water homeostasis in the context of the state of brain activity.
Dr. Nedergaard is Professor of Glial Cell Biology at the Center for Neuroscience at the University of Copenhagen, Denmark and Dean’s Professor and Co-Director of the Center for Translational Neuromedicine at the University of Rochester Medical Center in Rochester, NY. Her multiple interests range from basic research on neuron-glia interactions to their role in aging, small vessel disease, seizure disorders and cerebral blood flow. Forefront amongst her discovery is the identification of the glymphatic system, a brain equivalent of the lymphatic system within which cerebrospinal fluid diffuses rapidly and mixes with interstitial fluids, thereby filtering metabolic byproducts that accumulate due to neuronal activity. The glymphatic system dramatically expands during sleep compared to waking – brain cleaning and detoxification is thus greatly facilitated during sleep, providing a novel and direct explanation for what we all generally consider sleep’s restorative effect. Dr. Nedergaard is an elected member of the Royal Danish Academy of Sciences and Letters, Royal Academy of Pharmacy of Spain, and Academia Europaea. In 2015, she received the Newcomb Cleveland Prize from AAAS and the Alzheimer Prize in Denmark.