Imagine a star-shaped cell in the brain, reaching out with long, thin extensions to surround nearby neurons. This cell is called an astrocyte. For years, scientists believed astrocytes mainly acted as caretakers, helping hold neurons together and keeping brain circuits running smoothly.

New research is now challenging that idea. These widely distributed "support cells" appear to be just as important as neurons when it comes to forming and controlling fear memories.

"Astrocytes are interwoven among neurons in the brain, and it seemed unlikely they were there just for housekeeping.…