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The nightlife of the brain

Wednesday, February 11, 2015


Maiken Nedergaard, M.D., Ph.D.
Frank P. Smith Professor, Neurosurgery
Co-Director, Center for Translational Neuromedicine
University of Rochester

Dr. Nedergaard’s multiple interests range from basic research on neuron-glia interactions to their role in aging, small-vessel disease, seizure disorders, and cerebral blood flow. One of her most important discoveries was the identification of the glymphatic system, the brain equivalent of the lymphatic system. In the glymphatic system, the cerebrospinal fluid diffuses rapidly and mixes with interstitial fluids, thereby filtering metabolic byproducts that accumulate during neuronal activity. In 2013, Dr. Nedergaard published a landmark study in Science showing that the glymphatic system dramatically expands during sleep compared to waking. Her finding that brain cleaning and detoxification is greatly facilitated during sleep, may provide a novel and direct explanation for what we all generally consider sleep’s restorative effect.


Dr. Nedergaard and her colleagues recently described a macroscopic pathway in the central nervous system: the glymphatic system, which facilitates the clearance of interstitial waste products from neuronal metabolism. The glymphatic clearance of macromolecules is driven by cerebrospinal fluid (CSF) that flows along para-arterial spaces and through the brain parenchyma via support from astroglial aquaporin-4 water channels. The glymphatic circulation constitutes a complete anatomical pathway: para-arterial CSF exchanges with the interstitial fluid, solutes collect along para-venous spaces, and then drain into the vessels of the lymphatic system for ultimate excretion from the kidney or degradation in the liver. Because the glymphatic system is only active during sleep, it represents a novel and unexplored pathway for understanding the biological necessity for sleep.

The page was last updated on Thursday, March 26, 2015 - 5:58pm