Nedergaard and her colleagues dubbed the newfound plumbing the glymphatic system, after neural tissue called glial cells, which power the flow of cerebrospinal fluid.

Glial cells do this by growing their "feet" around vessels and veins that carry blood, forming a sort of pipe around a pipe.

Tiny pores in this outer pipe then suck nutrient-rich cerebrospinal fluid from the blood vessels into channels dense with nerve cells, and pores at other locations pump the fluid out. The process simultaneously carries away the brain's waste while feeding its cells.

A special two-photon microscope, whose infrared light allows a deep, clear look into living brain tissue without harming it is revolutionizing neuroscience, and they've become commercially available in the past five or six years.