While touch always involves awareness, it also sometimes involves emotion. For example, picking up a spoon triggers no real emotion, while feeling a gentle caress often does. Now, scientists in the Cell Press journal Neuron describe a system of slowly conducting nerves in the skin that respond to such gentle touch. Using a range of scientific techniques, investigators are beginning to characterize these nerves and to describe the fundamental role they play in our lives as a social species – from a nurturing touch to an infant to a reassuring pat on the back. Their work also suggests that this soft touch wiring may go awry in disorders such as autism.
The nerves that respond to gentle touch, called c-tactile afferents (CTs), are similar to those that detect pain, but they serve an opposite function: they relay events that are neither threatening nor tissue-damaging but are instead rewarding and pleasant.