Areas people like to be caressed match up with nerve fibers

WASHINGTON — Being stroked in the right place at the right speed activates specialized nerve fibers. The caresses that people rate most pleasant line up with the probable locations of the fibers on the skin, new research suggests.

“Touch is important in terms of our physical health and our psychological well-being,” said Susannah Walker, who presented the research November 17 at the annual meeting of the Society for Neuroscience. “But very little attention has been paid to the neurological basis of that effect.”

Sensors in the skin known as C-tactile afferents respond strongly to being stroked at between three and 10 centimeters per second. The sensors send signals to the brain that make touch rewarding, says Walker, a neuroscientist at Liverpool John Moores University in England.

Walker and a colleague played videos for 93 participants, showing a hand caressing a person’s palm, back, shoulder or forearm, either at 5 cm/s or 30 cm/s.

Participants rated the 5 cm/s stroking — the best speed to get the skin’s sensors firing — as the most pleasant, except on the palm, where there are no stroking sensors. The back got the highest pleasantness ratings, forearms lowest.

The spots where people like to be touched may not line up with the areas traditionally considered most sensitive. Though less finely attuned to texture or temperature than the hands or face, the back and shoulders are sensitive to a different, social sort of touch.