Wind on your cheek, a burn from a hot pan, the rumble of a passing train: all are detected by an intricate network of sensors embedded in the skin, and all arrive in the brain as distinct experiences. David Ginty has spent his career cataloguing the neurons responsible, and the variety he has found is remarkable.
Different classes of sensory neurons respond to different kinds of mechanical input. Some detect a gentle stroke, others sustained pressure, vibration or a sharp poke. Their endings are structured in ways that tune them to particular stimuli, and they connect to distinct pathways in the spinal cord and brain. The result is a system capable of extraordinary discrimination, able to tell silk from sandpaper at a touch.
Ginty's work has also revealed how much of this circuitry is established early in development and how it can be disrupted by injury or disease. Chronic pain, numbness and hypersensitivity all reflect failures somewhere in the chain, and mapping the components is a prerequisite for repairing them.
