This morning, before your day began, chances are you gave yourself quick look in the mirror and spent a few moments fiddling around with the hair on top of your head, probably blissfully unaware there’s much more important “hair” laying inside your skull.
Cells that line the brain cavity are armed with tiny hair-like protrusions called cilia. The role of these mysterious little features has long been overlooked by science, but a new study confirms that they are highly important and may even be essential in the development of the brain.
The research, published this week in the journal Current Biology, has shed more light onto how these hair-like fingers help to push along fluid around the brain’s four fluid-filled ventricles, helping to keep a constant circulation of cerebrospinal fluid throughout your noggin. In turn, the flow of fluid helps keep the brain healthy and promote the development of new nerve cells.
"Several theories exist, but for many years this circulation of fluid has been recognized as supplying nutrients to the brain, while also removing waste products," senior researcher Nathalie Jurisch-Yaksi of the Norwegian University of Science and Technology's Kavli Institute said in a statement.
"The cerebrospinal fluid flow also contributes to transmitting molecular signals across the brain," added Emre Yaksi, a professor at the Kavli Institute.
To delve deeper into the murky world of brain hairs and fluid, the researchers studied zebrafish. Zebrafish are often used as a model organism in research about genes and vertebrate development because their eggs are fertilized and develop outside the mother's body. They share a surprising amount of similarities with humans genetically.
Their findings showed a number of insights into the nature of cilia and brain flow. First up, they appear to push fluid along with a “propeller motion,” much like the tail of a sperm. They also discovered that, when the organism is at rest, the flow stays relatively local and ventricular flow remains compartmentalized to each of the brain’s four fluid-filled cavities. Then, when the body starts moving, exchange of fluid between the different ventricles sparks up.
Most crucially of all, the research highlights how new neurons come to “life”. The neurons are created near the wall of the fluid-filled brain ventricles and then pushed around to different portions of the brain through the flow of cerebrospinal fluid.
These initial findings are fascinating but there is still much more to unravel about cilia and cerebrospinal fluid. Next, they hope to further their understanding of how these hairs react to different environments and different times of day, as well as how this affects the flow of that all-important brain fluid