Self-cleaning brains

WE HAVE A BUILT-IN SYSTEM TO CLEAR TOXIC WASTE FROM BETWEEN OUR BRAIN CELLS.

Sleep is one of the brain’s great mysteries, but research on mice has revealed an intriguing night time cleanup system. The brain is shielded by a barrier made and maintained by cells called astrocytes. They hug the blood vessels, controlling what’s allowed in and out, and a space between the vessel wall and these cells seems to play a crucial role in keeping the brain clean.

At night, the astrocytes relax their grip and the space fills up with a clear liquid called cerebrospinal fluid (CSF). It’s pushed along by the movement of the blood vessels underneath, swishing up through the astrocytes and out into the spaces between brain cells. As it passes, it picks up waste and debris, carrying the particles back towards the bloodstream so that they can be removed from the brain.

FLOW

At night, the channels around the blood vessels widen, allowing CSF to sweep through the brain.

CEREBROSPINAL FLUID (CSF)

The brain is bathed in clear liquid that carries nutrients in and waste products out.

ASTROCYTE

Star-shaped support cells surround the blood vessels in the brain.

END FOOT

Astrocytes have long projections called ‘feet’, which come together to create channels around the blood vessels.

WASTE

Brain cells are constantly creating waste products that can cause damage if they’re allowed to build up.

WASTE REMOVAL

As the CSF flows across the brain, the waste products are carried towards vessels where they can be removed via the bloodstream.