Experts Discovered a New Function of Over Half Our Brain Cells
The lesser known astrocyte cells
Hiya!
I’ve always felt drawn to the human brain and its mysterious inner workings. As a kid, I considered a career as a neurosurgeon or psychologist — until I discovered how much school was involved. Then in my twenties, I had brain surgery to correct a cavernous malformation and recovered in a fraction of the expected time frame.
Of course, personal stories aside, I’m not alone in my fascination. We all are on some level. Brilliant minds from multiple fields have dedicated their lives to studying the brain and mind, and we’ve learned a ton. Yet, we don’t know how much we don’t know — a lesson scientists were recently reminded of.
Recapping Some Basics
Before we can understand what the researchers discovered, we should review a few basics. Specifically when it comes to relevant cells and mechanics of the brain, beginning with neurons.
As you know, neurons are fundamental cells in our brain and nervous system that receive information from the outside world via our senses. They also send motor signals to our muscles for us to move through our nervous system.
Neurons communicate using neurotransmitters — chemicals that allow electrical signals to be sent and received throughout the body. Lastly, synapses connect the small gaps between neurons and convert electrical signals into neurotransmitters.
So far, this information is pretty standard and considered established within the scientific community. Lesser well-known, though similarly thought by experts to be settled, is another cell known as astrocytes — which constitute nearly half of all the cells in our brain.
Scientists have already discovered several essential roles of astrocytes. They guide the growth of axons, part of a neuron that conducts its electrical impulses. Astrocytes monitor and control synaptic function, along with the levels of neurotransmitters and ions like potassium. They also provide metabolic support, react to injuries, and build the blood-brain barrier.
That’s quite a few jobs for these tiny star-shaped cells, so it’s understandable experts assumed that’s all there is — but it turns out astrocytes do much more.
New Role of Astrocytes in the Brain
Until recently, scientists thought neurons to be the most essential cells in the brain because they’re electrically active and because they use these electric signals and neurotransmitters to communicate. On the other hand, astrocytes have numerous vital functions but weren’t thought to be electrically active.
Until now.
Researchers at Tufts University School of Medicine used new technology to analyze and image the electrical properties of interactions between brain cells for the first time ever. They published their findings in April of 2022 in the journal Nature Neuroscience.
The researchers found that astrocytes, too, are “electrically alive.” Interestingly, the electrical activity of astrocytes changes how neurons function. Remember when I said astrocytes monitor and control synaptic function and the levels of neurotransmitters and ions like potassium that neurons produce?
Well, the study shows the potassium ions released by neurons alter the electrical activity of astrocytes and, in turn, how they control the neurotransmitters. Associate professor of neuroscience at the School of Medicine and Graduate School of Biomedical Sciences, and corresponding author on a paper, Chris Dulla summarizes:
"So the neuron is controlling what the astrocyte is doing, and they are communicating back and forth. Neurons and astrocytes talk with each other in a way that has not been known about before.”
I should note that the study was conducted on the brains of mice, not humans. Though there are reasons mice (and rats) are used as study subjects—they’re anatomically, physiologically, and genetically similar to us. Regardless, the researcher’s discovery about astrocytes unleashes unexplored questions for further research.
In the Future
Knowing astrocytes are electrically active and can communicate with neurons in this way means we’re forced to review the other roles astrocytes are responsible for. Does this new information change other interactions in the brain, such as how the cells influence neurological diseases?
Take Alzheimer’s disease, for example. In an article by Medicalxpress, Dulla explains that even though controlling neurotransmitters is one of the astrocytes’ primary jobs, they don’t perform this task in the brains of people with Alzheimer’s. They often don’t in the brains of those who suffer some brain injuries and epilepsy, either.
Before Dulla’s study, experts had a few ideas behind this strange behavior. One was that a protein may be missing, or the person had some kind of mutation preventing a protein from working. Another points to a potential build-up of extracellular potassium. Regarding the latter, the study helps explain how astrocytes clean the potassium build-up and maintain an excitable balance.
Of course, knowing this new and crucial role astrocytes play in our brains means researchers are screening drugs in use today to guage their effects on the interactions between neurons and astrocytes — and being scientists, they also want to see if they can use any existing drugs to intentionally manipulate these interactions.
As mentioned, the discovery was only possible due to new technology. The tool uses light to image electrical activity in the brain in a way never achieved before. The technology can also image potassium activity within the brain for the first time. So, it could shine a light on the role potassium has in our metabolism, sleep, or brain infections/injuries. Who knows what this information will teach us?
Perspective Shift
We have a habit of discovering one or two things about something and deciding that’s all it is or does. Sometimes, years, decades, or centuries later, someone becomes curious and investigates it again, only to discover something new.
This happens alllllll the time.
Science is full of examples, and the delay between discoveries is often due to technological limitations. The role and activity of astrocytes within the brain is just one example. Scientists learned of many functions of the astrocytes but required new technology before learning they, too, are electrically active.
Now, as with all new discoveries, we need to review all previous knowledge regarding medication, mental illnesses, and brain diseases with this new information in mind.
Sometimes though, it isn’t equipment that delays our discoveries. Consider a book you thought you understood, only to reread it years later to discover a whole new meaning within the story. How many times have you only known one or two things about someone and assumed you knew “who they are,” only to later find those things don’t represent them as well as you thought?
I suppose the important thing isn’t how long it takes or what’s responsible for our findings, but what we do with the information once we get it.
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