Separate teams of investigators have reported new insights into how the brain disposes of metabolic waste via the glia-based lymphatic system, or glymph system. In two papers published in Nature on Feb. 28, 2024, scientists from Washington University in St. Louis described how in sleeping animals, the synchronized activity of neurons drove ionic gradients that facilitated the movement of fluid through brain tissue. And researchers from the Massachusetts Institute of Technology showed that, in a mouse model of Alzheimer’s disease (AD), the glymphatic system mediated clearance of amyloid-β after sensory stimulation at a 40-Hertz rhythm.