Normal Brain Activity Linked to DNA Damage

Brain activity from experiences as common as exploring new locations surprisingly damages the noggin's DNA, hinting that such disruptions may be a key part of thinking, learning and memory, researchers say.

This damage normally heals rapidly, but abnormal proteins seen in Alzheimer's disease can increase this damage further, perhaps overwhelming the ability of brain cells to heal it. Further research into preventing this damage might help treat brain disorders, scientists added.

Explorer mice

Scientists analyzed young adult mice after they were placed into new, larger cages with different toys and odors that they were allowed to explore for two hours. They measured brain levels of a protein known as gamma-H2A.X, which accumulates when breaks occur in double-stranded molecules of DNA.

"DNA comes in double strands, and has the shape of a twisted ladder," said researcher Lennart Mucke, a neurologist and neuroscientist at the Gladstone Institute of Neurological Disease and the University of California at San Francisco. "Breaks in one strand, in one rail of the ladder, occur quite frequently, but breaking both takes quite a bit of damage and, in the brain, was thought to happen mostly in the context of disease." [10 Odd Facts About the Brain]

Unexpectedly, the researchers found such breaks also happened in the neurons of perfectly healthy mice, with up to six times more breaks in the neurons of explorer mice than in mice that remained in their home cages.

"Breaks of double strands of DNA seem to be a part of normal healthy brain activity," Mucke told LiveScience.

These DNA breaks occurred in various brain regions, especially in the dentate gyrus, an area necessary for spatial memory.

"It is both novel and intriguing, [the] team's finding that the accumulation and repair of DSBs [double-strand breaks] may be part of normal learning," said neuroscientist Fred Gage, of the Salk Institute, who did not take part in this study.

Mystery of DNA breaks

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Normal Brain Activity Linked to DNA Damage