Credit: Daniel O’Connor, Ph.D., Johns Hopkins University School of Medicine
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.