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The brain’s helper cells have a hand in learning fear

Astrocytes in the hippocampus may send signals that promote memories of trauma

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2:30pm, November 15, 2017
astrocyte

NEW ROLE  A kind of brain cell called an astrocyte (shown) may help nerve cells in the hippocampus form traumatic memories, a study in rats suggests.

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WASHINGTON, D.C. — Helper cells in the brain just got tagged with a new job — forming traumatic memories.

When rats experience trauma, cells in the hippocampus — an area important for learning — produce signals for inflammation, helping to create a potent memory. But most of those signals aren’t coming from the nerve cells, researchers reported November 15 at the Society for Neuroscience meeting.

Instead, more than 90 percent of a key inflammation protein comes from astrocytes. This role in memory formation adds to the repertoire of these starburst-shaped cells, once believed to be responsible for only providing food and support to more important brain cells (SN Online: 8/4/15).  

The work could provide new insight into how the brain creates negative memories that contribute to post-traumatic stress disorder, said Meghan Jones, a neuroscientist at the University of North Carolina at Chapel Hill.

Jones and her colleagues gave rats a short series of foot shocks painful enough to “make you curse,” she said. A week after that harrowing experience, rats confronted with a milder shock remained jumpy. In some rats, Jones and her colleagues inhibited astrocyte activity during the original trauma, which prevented the cells from releasing the inflammation protein. Those rats kept their cool in the face of the milder shock. 

These preliminary results show that neurons get a lot of help in creating painful memories.  Studies like these are “changing how we think about the circuitry that’s involved in depression and post-traumatic stress disorder,” says neuroscientist Georgia Hodes of Virginia Tech in Blacksburg. “Everyone’s been focused on what neurons are doing. [This is] showing an important effect of cells we thought of as only being supportive.”

Citations

M.E. Jones et al. Neuroimmune signaling in stress-enhanced fear learning, an animal model of post-traumatic stress disorder. Society for Neuroscience annual meeting, Washington, D.C., November 15, 2017.

Further Reading

L. Sanders. Gift-giving brain cells are lifeline to injured nerve cells. Science News Online, July 29, 2016.

L. Sanders. Astrocytes help speed up brain’s messages. Science News Online, August 4, 2015.

B. Bower. Till IL-6 Do Us Part: Elderly caregivers show harmful immune effect. Science News. Vol. 164, July 5, 2003, p. 5.

N. Seppa. Chronic stress can wreak havoc on the body. Science News. Vol. 187, March 7, 2015, p. 18.

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