Methylate to memorize

Achild reaching to touch a hot kettle will be either severely scolded or severely scalded. Learning to avoid hot kettles in the future might be thanks to the state of DNA methylation in the child's hippocampus, according to Courtney Miller and David Sweatt (University of Alabama, Birmingham, AL).

The pair found that the level of DNA-methylating enzymes (DNMTs) increased in the hippocampus when rats learned a conditioned response. For conditioning, rats were placed in an unfamiliar chamber, left to explore for a few minutes, and then given an electric shock and removed from the chamber. When the rats were put back in the chamber a day later, they froze in anticipation of the shock.

This associative learning was forgotten, however, when the rats were given a DNMT inhibitor immediately after...