Nerves dedicated to creating these feelings have been identified and artificially stimulated in mice, leading to hope that the work could aid the development of drugs that relieve pain or stress.

Some nerves rapidly transmit sensations of touch or pain to the brain, but others work much more slowly. These C-tactile fibres, as they are known in humans, are found under hairy skin and respond to stroking.

David Anderson at the California Institute of Technology in Pasadena and colleagues used calcium imaging to identify similar bundles of nerves in mice.