19:00 28 July 02
NewScientist.com news service
Scientists have discovered why being cuddled feels so good - human skin has a special network of nerves that stimulate a pleasurable response to stroking.
The revelation came after doctors realised that a woman with no sense of touch still felt a "pleasant" sensation when her skin was caressed.
Normal touch is transmitted to the brain through a network of fast-conducting nerves, called myelinated fibres, which carry signals at 60 metres per second. But there is a second slow-conducting nerve network of unmyelinated fibres, called C-tactile (CT), the role of which was unknown. The CT network carries signals at just one metre per second.
"It must be used for unconscious aspects of touch because it is so slow," says Håkan Olausson, who led the study at the Department of Clinical Neurophysiology at Sahlgrenska University Hospital, Sweden. "It seems the CT network conveys emotions, or a sense of self."
"This study definitely helps our understanding of how touch systems work," says Brian Fiske, assistant editor at Nature Neuroscience. "The researchers were very fortunate to have found a patient who had lost the main touch receptors but still had the slow CT fibres."
Journal reference: Nature Neuroscience (DOI: 10.1038/nn896)
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