ARI SHAPIRO, HOST:
There's a big change happening in neuroscience. Researchers are taking a closer look at cells that were once dismissed as merely the glue that holds a brain together. They're also looking at how those cells can cause inflammation and immune response in the brain. NPR's Jon Hamilton reports from the Society for Neuroscience meeting in Chicago.
JON HAMILTON, BYLINE: This meeting used to be all about neurons, the brain cells that produce electrical signals and allow memory and thought. But stroll through the thousands of posters at this year's event, and everywhere you see research on inflammation and cells known broadly as glia, which means glue in ancient Greek. Priya Prakash, a post-doc at NYU Grossman School of Medicine, is standing next to her poster.
PRIYA PRAKASH: I am studying an extremely rare movement disorder called X-linked dystonia parkinsonism.
HAMILTON: Her poster describes developing a mouse model of the disease, which resembles Parkinson's. And that model shows both inflammation and a key role for glial cells called oligodendrocytes, which provide insulation for nerve fibers. Prakash says her team didn't expect them to play a role in this disorder.
PRAKASH: So that was, like, a big surprise for us. And now we're really, like, changing our tracks to really focus on oligodendrocytes.
HAMILTON: Neuroscience gets its name from neurons. But Shane Liddelow, Prakash's supervisor at NYU, says, in fact, neurons make up only about half the cells in a brain.
SHANE LIDDELOW: The other half is all of these glial cells and these immune cells. And so to properly understand neurodevelopment and neurodegeneration dysfunction, you can't study only half of the brain. You have to study all of the brain.
HAMILTON: Liddelow says he's noticed a big change at the neuroscience meeting.
LIDDELOW: So there is not a poster on the floor outside here that doesn't have a contribution from these glial neuroimmune components.
HAMILTON: Take research on fear. One of the speakers at a media panel was Olena Bukalo of the National Institutes of Health. She studied mice, who tend to freeze when they're frightened. Bukalo found that in these rodents, fear memories are linked to another type of glial cell known as an astrocyte.
OLENA BUKALO: So when animal freeze a lot, astrocytes' activity going high. When animal are not freezing or in low fear state, astrocytes' activity is not as high.
HAMILTON: Bukalo says astrocytes also seem to reorganize the neurons that hold onto fearful memories. A few years ago, she says, scientists assumed that fear-related conditions like PTSD were caused primarily by neurons.
BUKALO: But recently we're realizing that glia is also play essential role in modulating, like, cognitive processing, including memory.
HAMILTON: Several glial cells are involved in both the brain's immune response and inflammation, though scientists are still trying to figure out how the system works. And even immune cells outside the brain can contribute to neurological problems. Freya Shepherd, a graduate student at Cardiff University, described how the behavior of mice changed when her team eliminated cells called Tregs, which usually keep the immune system from overreacting.
FREYA SHEPHERD: With the removal of Tregs, there is an immune activation, and that immune activation is related to increases in anxiety-like behaviors in mice.
HAMILTON: A finding that could explain why many patients with depression and anxiety have signs of inflammation in the brain. One presentation even looked at how prenatal exposure to cocaine might lead to mental health problems later in life. Keith Murphy of University College Dublin said brain cells in the lab began to grow abnormally when given the drug.
KEITH MURPHY: There is a very substantial increase in the number of inflammatory astrocytes present, and so cocaine is clearly activating an immune response in the developing tissue.
HAMILTON: One more piece of evidence that neuroscience is no longer all about neurons. Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.
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