“It has long been recognized that touch plays an important role in many forms of social communication and a number of theories have been proposed to explain observations and beliefs about the “power of touch.” Here, we propose that a class of low-threshold mechanosensitive C fibers that innervate the hairy skin represent the neurobiological substrate for the affective and rewarding properties of touch….In a wider perspective, the [C-tactile afferents (CTs)] may be regarded as an afferent system that is basically concerned with the representation of self, rather than external events, as conjectured by Craig (2002). The role of CTs as an afferent branch of a system guarding the well-being of the body would be to signal the reward and reassurance afforded by physical closeness of a caregiver, partner, etc. Many questions, however, still need to be addressed, and answered, with regard to the role of CTs, such as the absence of CT nerves in glabrous skin. Their precise anatomical location in human hairy skin is also unknown, and we do not know anything about their receptor neurobiology. Behavioral and neuroimaging studies (PET and fMRI) are addressing these issues, and there is increasing evidence for a different central neural representation to stroking hairy as opposed to glabrous skin in neurotypical and nonneurotypical populations in limbic brain structures rather than primary somatosensory structure areas (McGlone et al., 2012, Gordon et al., 2013 and Voos et al., 2013). The significant advances made in understanding the C fiber “pain” system have been made possible because of the multidisciplinary efforts of scientists and clinicians from diverse backgrounds—the same will need to be the case for the C fiber “pleasure” system.”
Basically – in addition to neurons in the skin that send information to the brain about the temperature and texture of what is being touched, there are neurons that send information about the positive emotional value of the touch. Which is lovely, and a reminder that physical and psychological/mental systems are deeply intertwined in the brain.
Press about it – “Further research on CTs may help investigators develop therapies for autistic patients and individuals who lacked adequate nurturing touch as children. Also, a better understanding of how nerves that relay rewarding sensations interact with those that signal pain could provide insights into new treatments for certain types of pain.” http://www.sciencedaily.com/
Related: "9 surprising facts about the sense of touch"
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