Brain's Capillaries web banner (IMAGE) University of Maryland School of Medicine Caption Pericytes on the brain's capillaries sense sugar and when levels are low they signal for blood vessels to dilate. Credit UMSOM Usage Restrictions Credit source 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.