Amygdala Methyl (IMAGE) Duke University Caption An artist's conception shows how molecules called methyl groups attach to a specific stretch of DNA, changing expression of the serotonin transporter gene in a way that ultimately shapes individual differences in the brain's reactivity to threat. The methyl groups in this diagram are overlaid on the amygdala of the brain, where threat perception occurs. Credit Annchen Knodt, Duke University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.