Brain response to placebo (image) University of Michigan Health System Share Print E-Mail Caption These images created from data gathered on PET scanners shows the areas of the brain where levels of natural mu-opioid painkillers rose in healthy volunteers who received a painful injection followed by a placebo. This response corresponded with certain personality traits. Credit Zubieta laboratory, University of Michigan Usage Restrictions None Share Print E-Mail 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.