Called SLYM (subarachnoid lymphatic-like membrane), she is very thin—hence the pun with slim, or thin in English): barely a few cells thick in some places. It is located in the subarachnoid spacewhich separates two of these membranes, called arachnoid and pia mater.
It is too thin to be detected by modern technologies that can observe brain activity from the outside. And it disintegrates when the brain is removed from the skull during an autopsy. Researchers you Danemark and the United States that describe its existence January 6 in the review Science explain that they first used genetic markers in mice to spot it, then confirmed its existence by dissolving the skulls of bodies donated for research.
The link between this discovery and waste disposal: our brain has a waste disposal system which is unique to it, called the glymphatic system. Discovered about ten years ago, it is composed of so-called glial cells, which drain the waste produced by the other cells, to the outside. However, it turns out that this SLYM layer separates this “circulation” of waste from the cerebrospinal fluid which is essential for the proper functioning of our gray matter.