Brain "stress test" (IMAGE) Keck School of Medicine of USC Caption Researchers developed a wearable device that can be used for non-invasive stroke risk assessment. The device uses speckle contrast optical spectroscopy to track changes in blood flow and volume in the brain during a breath-holding exercise. Credit Simon Mahler and Yu Xi Huang, California Institute of Technology Usage Restrictions none License Original 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.