Computer Screen Snapshot (image) University of Iowa Caption A computer screen shows the electrical activity of a specialized heart cell called a sinoatrial nodal cell. This type of cell can beat on its own without electrical stimulation, allowing scientist to see its activity when extracted. Information gleaned is contributing to understanding heart-pacing changes that occur during the body's "fight or flight" response to stress. Credit University of Iowa Usage Restrictions Image may only be used with appropriate caption or credit. 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.