Previously unidentified brain tissue is found by researchers.
The brain is surrounded by a novel structure that is only a few cells thick, according to researchers.
The subarachnoidal lymphatic-like membrane (SLYM), which contains immune cells and controls cerebrospinal fluid flow, serves as a protective barrier and smoothes interactions between the brain and skull.
The finding raises the possibility that the SLYM may be connected to some brain conditions.
Additionally, when developing treatments, researchers working on novel brain therapeutics will need to take the SLYM into consideration.
Inside and out, the human brain is a complexly organised organ.We continue to learn new things about the origins of cognition and consciousness decades after brain imaging became a common tool for scientists.
Researchers from the Universities of Rochester and Copenhagen announced their discovery of a layer of tissue surrounding the brains of both mice and humans on Thursday. Science provides a detailed account of the discovery.
The region of the subarachnoid space, which contains the cerebrospinal fluid surrounding the brain, is split into two compartments by the Subarachnoidal LYmphatic-like Membrane, or SLYM for short. High-resolution two-photon excitation microscopy was used by researchers in the labs of Maiken Nedergaard, co-director of the Center for Translational Neuromedicine, and Kjeld Mllgrd, a professor of neuroanatomy, to identify the thin layer, which is only a few cells thick.
The method, when combined with fluorescent protein dyes, created incredibly precise images on the micrometre scale inside of living organisms.
Following the discovery of the structure, the researchers performed numerous mouse experiments to ascertain its purpose.
They investigated what could pass the barrier and what couldn’t using dyed materials of different shapes, sizes, and properties.
Zooming in, they also observed that the SLYM is similar to the mesothelial tissue, a thin protective layer that covers other vital organs, and that it contains its own population of immune cells specific to the nervous system.
What the SLYM in the brain does
The researchers’ observations allowed them to draw the following conclusions about the SLYM:
- It serves as a safeguard for the brain.
- Immune cells use it as a platform to keep an eye out for inflammation and infections in the brain.
- As the brain moves inside the cranium, it lessens friction between the brain and skull.
- It controls the movement of the colourless fluid known as cerebrospinal fluid, which covers the exterior of the brain.
The most intriguing theorised function may be the fourth.
Recent research suggests that waste products from the brain that accumulate during wakefulness can be removed by the cerebrospinal fluid.
The glymphatic system eliminates any toxins while we sleep
The SLYM may actively permit “clean” cerebrospinal fluid to enter and “dirty” cerebrospinal fluid to exit the subarachnoid space surrounding the brain.
Nedergaard said in a statement that the discovery “gives us a much greater appreciation of the sophisticated role that cerebrospinal fluid plays not only in transporting and removing waste from the brain, but also in supporting its immune defences.”
The researchers note that the SLYM’s recent discovery provides new information about brain injury.
“Physical rupture of the SLYM could explain the prolonged suppression of glymphatic flow after traumatic brain injury as well as the increased posttraumatic risk of developing Alzheimer’s disease by altering cerebrospinal fluid flow patterns.”
Furthermore, they assert that damage to the SLYM may cause or exacerbate disorders of the central nervous system like multiple sclerosis, and that researchers working on novel brain therapeutics will need to consider the barrier when developing treatments.
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