PNN under Attack (image) University of Queensland Share Print E-Mail Caption UQ researchers propose that when vitamin D levels drop, certain enzymes become unchecked and begin to break down perineuronal nets. Credit Nick Valmas, The University of Queensland Usage Restrictions Only to be used with attribution. 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.