Forget body hair, the most important hairs are inside your brain

Cilia are hairlike structures that sprout from the surface of different cells in the body, and can be found throughout the body in the brain, kidneys, and lungs.

In cavities in the brain, cilia play a crucial role in brain development and health, but it had not been well understood just how cilia impact brain activity.

Cilia dysfunction and defective cilia have been linked to scoliosis and hydrocephalus which is when water builds up in the cavities of the brain.

In the hopes of understanding cilia and their function in the brain’s cavities, researchers from the Yaksi group at Kavli Institute for Systems Neuroscience at the Norwegian University of Science and Technology (NTNU) examined cilia and cerebrospinal fluid movement in zebrafish larvae.

A study detailing the research was published in the journal Current Biology, and the results show how cilia function in the brain.

Zebrafish were used for the study because they are an excellent model for humans. The fish are vertebrates and transparent in their larval stage which allowed the researchers a rare inside look at brain activity and development in the growing fish.

“We could even investigate each individual cell and cilia,” said Christa Ringers, a co-author of the study.
The human brain has cavities called ventricles that are filled with cerebrospinal fluid which is always moving and the researchers found that cilia are particularly important to the flow of fluid in the ventricles.

“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,” said Nathalie Jurisch-Yaksi, the senior researcher for the study.

Cilia are grouped into different zones in the ventricles, and these groupings help with direction and flow of ventricle fluid.

The ventricles in the brain are all connected, and cilia in each ventricle seem to be interconnected to the other ventricles, and a steady flow of fluid is important to keeping the ducts between the ventricles open.

“If we stop the cilia’s motion, the ducts close,” said Jurisch-Yaksi.

Activity and heartbeat also influence this movement, according to the study.

“We found surprisingly little exchange of fluid between the ventricles as long as the fish were at rest, even though the heartbeat pulsations caused some flow between them,” said Emilie Willoch Olstad, the first author of the study.

The researchers noted that cilia in the ventricles are different from cilia in the lungs and other moving cilia in the body. Overall, the team found that cilia are crucial for directing the flow of cerebrospinal fluid and this, in turn, drive healthy neural development.  

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By Kay Vandette, Earth.com Staff Writer

Image Credit: Kavli Institute for Systems Neuroscience, Yaksi Group