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| © Andriy Onufriyenko, Getty Images |
By Tim Newcomb, Popular Mechanics
- There’s a newly discovered fourth membrane in the human brain.
- The thin brain barrier controls the flow of cerebrospinal fluid in and around the brain to support immune defense.
- The same membrane type also works in human lungs and hearts.
We just learned something about the human brain that proves we still have a lot to learn about the human brain: Turns out there’s a fourth membrane in the brain, according to a new study from the universities of Rochester and Copenhagen.
In the study, published in the journal Science, researchers say a previously unknown fourth membrane exists in the brain—located in the space below the arachnoid layer—to help control the flow of cerebrospinal fluid (CSF) and remove waste from the brain to support immune defense.
The researchers were only able to see the thin and delicate fourth membrane, which measures only a few cells in thickness and is tight enough to separate clean and dirty CSF, thanks to recent advancements in neuro-imaging and molecular biology. The fourth membrane could enable the flushing of toxic proteins associated with Alzheimer’s and other neurological diseases from the central nervous system.
The newly discovered fourth membrane, a mesothelium type that’s also found in human lungs and hearts, is known to surround and protect organs while containing immune cells. Along with flushing toxic CSF, the membrane prevents outside immune cells from entering and “appears to host its own population of central nervous system immune cells that use the Subarachnoidal Lymphatic-like Membrane for surveillance at the surface of brain, allowing them to scan passing CSF for signs of infection,” the study authors write.
It was previously known that dirty CSF can cause fatigue in humans, so researchers may be able to also understand how sleep can clear the brain of toxins and play a part in helping treat CNS diseases.
Scientists say the discovery of the new fourth membrane could possibly lead to improved drug delivery, fresh biological therapies, and a greater understanding of diseases. Not bad for such a thin brain barrier.
