In a mouse's hippocampus, brain cells known as microglia (red) can eliminate connections between nerve cells (blue) that are thought to store some types of memories.
Chao Wang
Immune cells in the brain chew up memories, a new study in mice shows.
The finding, published in the Feb. 7 Science, points to a completely new way that the brain forgets, says neuroscientist Paul Frankland of the Hospital for Sick Children Research Institute in Toronto, who wasn't involved in the study.
That may sound like a bad thing, but forgetting is just as important as remembering. "The world constantly changes," Frankland says, and getting rid of unimportant memories - such as a breakfast menu from two months ago - allows the brain to collect newer, more useful information.
Exactly how the brain stores memories is still debated, but many scientists suspect that connections between large groups of nerve cells are important (SN: 1/24/18). Forgetting likely involves destroying or changing these large webs of precise connections, called synapses, other lines of research have suggested. The new result shows that microglia, immune cells that can clear debris from the brain, "do exactly that," Frankland says.
