Mouse Touch (IMAGE) Johns Hopkins Medicine Caption Touch is normally active, resulting from self-motion. Merkel afferents (top right, green and magenta) "fired" action potentials (white) during both movement and touch as mice ran on a treadmill and moved their whiskers to explore. Merkel afferents were identified by genetically altering them to fire when exposed to blue light (bottom left, bolt), not just to movement and touch. Credit Daniel O'Connor, Ph.D., Johns Hopkins University School of Medicine 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.