/Twinkling, star-shaped brain cells may hold the key to why, how we sleep

Twinkling, star-shaped brain cells may hold the key to why, how we sleep

Summary: A new study published in the journal Current Biology suggests that star-shaped brain cells known as astrocytes could be as important to the regulation of sleep as neurons, the brain’s nerve cells.

Original author and publication date: Washington State University – September 24, 2020

Futurizonte Editor’s Note: If star-shaped brain cells makes us sleep, perhaps we sleep to reconnect with the stars. After all, we are stardust.

Astrocytes in the brain expressing a fluorescent calcium indicator captured with a two-photon microscope. Credit: Ashley Ingiosi, courtesy of Current Biology.
Astrocytes in the brain expressing a fluorescent calcium indicator captured with a two-photon microscope. Credit: Ashley Ingiosi, courtesy of Current Biology.

From the article:

Led by researchers at Washington State University’s Elson S. Floyd College of Medicine, the study builds new momentum toward ultimately solving the mystery of why we sleep and how sleep works in the brain. The discovery may also set the stage for potential future treatment strategies for sleep disorders and neurological diseases and other conditions associated with troubled sleep, such as PTSD, depression, Alzheimer’s disease, and autism spectrum disorder.

“What we know about sleep has been based largely on neurons,” said lead author and postdoctoral research associate Ashley Ingiosi.

Neurons, she explained, communicate through electrical signals that can be readily captured through electroencephalography (EEG). Astrocytes—a type of glial (or “glue”) cell that interacts with neurons—do not use electrical signals and instead use a process known as calcium signa

It was long thought that astrocytes—which can outnumber neurons by five to one—merely served a supportive role, without any direct involvement in behaviors and processes. Neuroscientists have only recently started to take a closer look at their potential role in various processes. And while a few studies have hinted that astrocytes may play a role in sleep, solid scientific tools to study their calcium activity have not been available until recently, Ingiosi said.

To delve deeper into astrocytes’ role in sleep, she and her coauthors used a rodent model to record astrocytes’ calcium activity throughout sleep and wake, as well as after sleep deprivation. They used a fluorescent calcium indicator that was imaged via tiny head-mounted microscopes that looked directly into the brains of mice as they moved around and behaved as they normally would. This indicator allowed the team to see calcium-driven fluorescent activity twinkling on and off in astrocytes during sleep and waking behaviors. Their one-of-a-kind methodology using these miniature microscopes allowed the team to conduct the first-ever study of astrocytes’ calcium activity in sleep in freely behaving animals.

The research team set out to answer two main questions: do astrocytes change dynamically across sleep and wake states like neurons do? And do astrocytes play a role in regulating sleep need, our natural drive to sleep?

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