As the central command centers for our bodies, our brains dictate who we are and how we live. And yet we know surprisingly little about them. While the cellular biology of this critical organ has been mapped out, scientists can’t really explain how the human brain operates. Now, a growing group of scientists believes solving some of the many mysteries of our minds—including what shapes consciousness and how to better treat neurodegenerative diseases—could lie in tiny star-shaped cells called astrocytes.
Researchers suggest astrocytes are both the “dark matter” and the “helicopter parents” of your brain, providing structural support around neurons and shaping your behavioral responses. In just the past 10 years, researchers have discovered that astrocytes appear to play an important role in your fear and anxiety responses, in regulating your emotions, and in your choice to persevere during a hard task, for example.
An emerging notion that astrocytes directly participate in behavior, cognition, and brain computation by actively shaping neuronal circuit activity is certainly turning conventional wisdom upside down, says Thomas Papouin, PhD, an assistant professor of neuroscience at Washington University School of Medicine who examines how astrocytes contribute to information processing. “As you can imagine, there’s an enormous amount of inertia from the field, given that since the very emergence of neuroscience as a discipline of its own, the focus has solely been on neurons.”
The neuron is one of two primary cell types in our brains: Neurons communicate via junctions called synapses to coordinate responses in our body. Glia are believed to mainly provide support functions. Derived from the Greek word for glue, glia—including astrocytes—account for nine out of every ten cells in the brain and are the web that holds neurons in place. Astrocytes in particular work to keep neurons fed and the brain in balance, but growing research shows they play a much larger role than previously thought.
Kevin Guttenplan, PhD, a postdoctoral fellow at Oregon Health & Science University (OHSU), says astrocytes are like the “dark matter” of the brain, the baffling substance in the universe that also acts like a glue, anchoring planets and holding galaxies together.
“As we tried to understand the way the universe works just using matter, we couldn’t quite explain it, and so we started investigating dark matter,” says Guttenplan, who works in the lab of neuroscientist Marc Freeman, PhD. “Similarly, for a long time we looked at neurons and assumed everything else wasn’t a concern. Now that we’re starting to include astrocytes, we’re going to have a much better ability to understand how the brain works.”
Findings about astrocytes over the past decade have steadily chipped away at traditional thinking that neurons alone rule the brain
Astrocytes first started to gain significant attention more than two decades ago when Stephen Smith, now an emeritus professor of neuroscience at Stanford University, and members of his lab first saw evidence that astrocytes appeared to be communicating during neuronal calcium release, which is fundamental in the control of synaptic activity and memory formation, among other important functions.
“This key observation by Stephen found that when you examined astrocytes in calcium signaling, it looked like they were doing more than just sitting there watching, which immediately led people to think maybe they’re actually parts of these circuits, too,” says Freeman, who is director of the Vollum Institute, an independent neuroscience research center at OHSU.
But what the field needed, Freeman says, was proof that a neuron releases a neurotransmitter, or chemical messenger, that binds to something on an astrocyte to alter the calcium signal, which then drives some change in downstream neuron activity. In 2016, Freeman and his lab did just that, showing in a paper published in Nature that astrocytes in the brains of fruit flies could alter certain types of neuron activity and were essential for multiple sensory-driven behaviors in the flies.
Since then, a multitude of studies from numerous labs worldwide have consistently documented the pivotal role of astrocytes in implementing circuit adaptations to changes in brain states, says Papouin.
For example, neuroscientist Misha Ahrens, PhD, a group leader at the Howard Hughes Medical Institute’s Janelia Research Campus, and a team of researchers investigating swimming actions in zebrafish in 2019 showed more evidence that astrocytes can perform computations related to behavior. In an experiment that repeatedly pushed the fish to make progress in a virtual reality–equipped swim chamber that mimicked the feeling of drifting backward no matter how hard they tried, Ahrens showed that the switch from “trying hard” to “giving up” is orchestrated by astrocytes.
“Astrocytes sense the repeated ‘failure’ signal and eventually shut off the circuit—in this case the motor circuit—that was responsible for the repeated attempts,” explains Papouin, who was not involved in the work. Follow-up work by Ahrens and others found that ketamine could reverse the fish’s instincts to “give up” by activating an astrocytic circuit, showing the cells are necessary for the drug’s positive effect of perseverance.
In his own work, Papouin and a team of researchers reported last year in Science that astrocytes in mice are responsible for modifying brain activity in response to norepinephrine, a stress hormone. In the same issue, Freeman and Guttenplan outlined “a mechanism by which astrocytes dynamically respond to and modulate neuronal activity in different brain regions and in different behavioral states.”
Collectively, these and other findings about astrocytes over the past decade have steadily chipped away at traditional thinking that neurons alone rule the brain, shifting at least part of the field toward a new focus. This year alone, studies have linked astrocytes to encoding fear and anxiety, playing a role in brain cancer progression, helping regulate emotional health, and much more.
“I like to think of them as helicopter parents,” says Freeman. “They keep neurons in a nice environment, they give them food, they clean up their messes. If there’s an injury, they take care of it. They just sort of do everything to try to take the workload off of the neurons, so they can focus on efficient firing.”
While the scientific view of astrocytes is shifting significantly, it’s important to note that nearly all experiments thus far have been done in animal models. Nestled in the safe and solid confines of our skull, the brain is extremely difficult to access, making it tough to study. So, what do we know for certain about the role of astrocytes in people?
“You could ask the same question of neurons in humans, and get a very poor answer,” says Freeman, noting that the only real tool we have for looking at activity in the brain is investigating it during surgeries, or using indirect measures that image things like blood flow to map activity. “We can’t image astrocyte activity in people yet, as it’s early days. But 10 years ago, I would say we didn’t really have the tools to do this, even in animal studies.”
However, animal models make for a good stand-in as technology catches up to the needs of current research, especially when the same processes are seen over different species, like flies, fish, and mice.
“The stuff that’s conserved is important; if a fruit fly has it and a mouse has it, almost certainly we have it,” Freeman says. “Plus, if you really want to understand how a brain works, you can’t ignore half of it.”
While researchers work hard to elucidate the roles of astrocytes, Freeman and Guttenplan say the public can sit back and enjoy whatever benefits the tiny cells might be bringing to their lives; there is likely little we can do to influence astrocyte health, because keeping the brain healthy is their job.
“If there were a lot of issues where astrocytes were getting super sickly over time, my guess is it would be very bad, like catastrophic,” Guttenplan says.
However, their role in keeping the brain happy should make them an excellent therapeutic target for fixing the things that go wrong in neurodegenerative diseases and psychiatric disorders.
“There are a huge number of stories in the mix trying to be published right now that just show place after place after place in the brain where astrocytes are doing really interesting things,” Freeman says. “I think they will be enormously important in a lot of sophisticated processes in the brain, but it’s going to take us a while to figure it out.”
February / March 2026
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December 2025 / January 2026
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October / November 2025
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➡ Inside the Secret Island Where Death Is Optional
➡ A Legendary Ship Sank Without Warning. Fifty Years Later, Science Could Finally Solve the Mystery of the Edmund Fitzgerald.
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August / September 2025
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➡ NASA Has a Plan to Save Earth from Planet-Destroying Asteroids. It Sounds Even Wilder than Science Fiction.
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June/July 2025
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➡ This Undersea Explorer Found America's Greatest Sunken Treasure. Then Things Got Really Weird.
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April/May 2025
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➡ Scientists Successfully Revive a Dead Brain, Redefining the Boundary Between Life and Death
➡ Fingerprints Keep Leading to Wrongful Convictions. Why Do Courts Still Rely on Them?
➡ For 80 Years, the North Sea Held a Deadly Killer. Now Scientists Are Racing to Defuse the Threat.
➡ They Built the Quietest Room in the World. Why Is Everyone So Afraid to Step Inside It?
February/March 2025
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➡ This Guy Says He Knows the Truth About UFOs. Should We Believe Him?
➡ Scientists Are Now One Step Away From Solving Nuclear Fusion—And Unlocking Unlimited Energy.
➡ A Million-Dollar Heist Rocked the Art World— Then Amateur Sleuths Cracked the Case
➡ A New Era of Missile Warfare Has Begun—and the U.S. Isn’t Ready
December/January 2025
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➡ A Clue Hidden in a 400-Year-Old Map Might Have Just Solved One of America's Greatest Mysteries
➡ Inside the Deranged Plot to Smuggle Cocaine With an Armed Soviet-Era Submarine
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October/November 2024
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➡ It Was Supposed to Be America's Greatest Victory in Space—Then It Became NASA’s Worst Nightmare
➡ The Sidewinder Missile Ruled the Air—Then the Soviets Stole the Design
August/September 2024
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➡ Russia Built a Stunning Rival to the Supersonic Concorde—and Then It Fell From the Sky
➡ A Navy Admiral Says Underwater UFOs Are a Threat—and the Pentagon is Withholding Secrets
June / July 2024
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➡4 Black Eggs Have Surfaced From the Depths of the Ocean— and the Mysterious Creatures Inside Are Baffling Science
➡ A $2 Million Treasure Appeared in a Kentucky Cornfield. No One Knows Where It Came From.
➡ A Million-Dollar Heist Rocked the Art World— Then Amateur Sleuths Cracked the Case
➡ A New Era of Missile Warfare Has Begun—and the U.S. Isn’t Ready
April May / 2024
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➡ A Staggering New Clue Emerges in the D.B. Cooper Hijacking Mystery
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February / March 2024
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➡ Scientists Believe They’ve Unlocked Consciousness—and It Connects to the Entire Universe
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➡ America Is Developing a New Nuclear Bomb—But Can’t Test Whether It Works
➡ The 8 Best, Expert-Recommended Solar-Powered Generators
Special Issue: Nukes
➡ How Deadly Nuclear Waste Is Menacing This St. Louis Neighborhood
➡ The Terrifying History of Russia's Nuclear Submarine Graveyard
➡ Strange Mutations in Stray Dogs Near Chernobyl Suggest They Are Rapidly Evolving
➡ America Dumped 56 Million Gallons of Radioactive Material Along the Columbia River—Then It Started to Leak
December 2023 / January 2024
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➡ A New Clue In Amelia Earhart's Disappearance Emerges From the Ocean
➡ How an Alleged Water Bandit Stole $25 Million in Water from Thirsty California Farms
➡ A Coal Mine Exploded and 300 Miners Died. What Went Wrong?
➡ China Just Built a Terrifying New Aircraft Carrier and May Soon Dominate the Seas
October / November 2023
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➡ How Rats Took Over Our Cities—And Why We Can't Stop Them
➡ This Language Is on the Verge of Extinction. Can It Be Saved?
➡ America's Deadliest Warplane Returns in a New Doomsday Role
➡ This Amateur Diving Group Kept Solving Cold Cases. Then Its Own Skeletons Surfaced.
➡ The Scientific Breakthrough That Could Put an End to Gray Hair.
August/September 2023
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➡ Immortality Is in Reach. But It’s Not What We Imagined.
➡ Your Next iPhone (and Nuclear Subs) Will Be Powered By Space Metal
➡Scientists Now Think We Can Build a Warp Drive
➡ China and Russia Have Cracked the Stealth Code. Can the U.S. Regain Air Dominance?
June/July 2023
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➡ The CIA’s Secret Plan to Build a Laser Beam Powered by the Human Mind
➡ The 747 Ruled the Skies—Then One Slammed Into a Mountain
➡The Race to Contain AI Before Singularity
➡ These Florida Homes Aren’t Just Hurricane-Proof—They’re Blueprints for the Future
April/May 2023
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➡ AI Is on the Cusp of Taking Control—This Is How It May All Go Wrong
➡ There’s No Weapon Russia Fears More Than the HIMARS Rocket Launcher
➡The Nuclear-Submarine Arms Race Is Getting Intense, and the U.S. Just Took a Massive Leap Forward
➡ Iran Is Becoming a Drone Superpower—By Stealing American Technology
February/March 2023
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➡ The Greatest Treasure Hunt in American History Ended—and Then Things Got Weird
➡ These Are the High-Powered Weapons Ukraine Needs to Send Russia Running
➡ The Secret War to Take Out Iran’s Fleet of F-14 Jets
➡ Russia Is Trying to Intimidate the U.S. with Hypersonic Missiles and Big, Scary Nukes—And It's More Than a Threat
December 2022/January 2023
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➡ Is Death Real?
➡ China and Russia Are Dominating the Hypersonic Arms Race—And It’s Not Even Close
➡ When the South Fork Dam Broke, a Pennsylvania City Washed Away. Which Town Is Next?
➡ The Navy’s New $13 Billion Aircraft Carrier Is Already Obsolete. This Weapon Can Save It.
October/November 2022
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➡ Can America's M1 Abrams Still Compete With China's and Russia's Latest Battle Tanks?
➡ Inside the Final Minutes of the Concorde Disaster—and How It Doomed Supersonic Travel for Decades
➡ How the Massive Cargo Ship Felicity Ace Sank, Taking $400 Million Worth of Exotic Supercars With It
➡ I Turned My Old Gas-Guzzler Into a Zippy EV for $15,000
August/September 2022
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Featuring:
➡ Cosmic Secrets of the 17 Most Powerful Mega-Telescopes on Earth—and Beyond
➡ Can the Air Force's Secret, Hypersonic Jet Reclaim the Skies From Russia and China?
➡ For 50 Years, the Zodiac Killer's 340 Cipher Stumped the FBI—Then Three Amateurs Cracked the Code
➡ America's Most Fearsome Howitzer Has Entered the War in Ukraine
June/July 2022
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Featuring:
➡ Every Single Drone Fighting in the Skies Over Ukraine
➡ How to Buy a New Car in 2022 Without Getting Fleeced
➡ This Megastructure Could Keep Us Alive Forever
➡ The Race to Revolutionize EV Batteries
Katie Neith is a science writer based in Los Angeles. Her favorite celebrity sightings are the great horned owls that live in her hillside neighborhood. A recent graduate of the Johns Hopkins MA in Science Writing program, her work has appeared in Nautilus and Live Science, among other publications. Connect: www.katieneith.com
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