Gray Matter (IMAGE) University of Pennsylvania School of Medicine Caption MRI-derived gray matter measures, density, volume, mass, and cortical thickness, show distinct age and sex effects, as well as age-dependent intermodal correlations around adolescence. Credit Penn Medicine 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.