Smaller than a Needle's Eye (IMAGE) Washington University School of Medicine Caption This implantable LED light can activate brain cells to release dopamine and is smaller than the eye of a needle. Credit John A Rogers, Ph.D. and Michael R. Bruchas, Ph.D. 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.