Social touch modulates endogenous μ-opioid system activity in humans

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Nummenmaa, Lauri; Tuominen, Lauri; Dunbar, Robin; Hirvonen, Jussi; Manninen, Sandra; Arponen, Eveliina; Machin, Anna; Hari, Riitta; Jääskeläinen, Iiro P.; Sams, Mikko
Year of Publication: 2016
Journal: NeuroImage
Volume: 138
Pagination: 242 - 247
Date Published: 2016/09/01/
Publication Language: eng
ISBN Number: 1053-8119
Keywords: Bonding, Opioids, PET, Somatosensory, Touching

In non-human primates, opioid-receptor blockade increases social grooming, and the endogenous opioid system has therefore been hypothesized to support maintenance of long-term relationships in humans as well. Here we tested whether social touch modulates opioidergic activation in humans using in vivo positron emission tomography (PET). Eighteen male participants underwent two PET scans with [11C]carfentanil, a ligand specific to μ-opioid receptors (MOR). During the social touch scan, the participants lay in the scanner while their partners caressed their bodies in a non-sexual fashion. In the baseline scan, participants lay alone in the scanner. Social touch triggered pleasurable sensations and increased MOR availability in the thalamus, striatum, and frontal, cingulate, and insular cortices. Modulation of activity of the opioid system by social touching might provide a neurochemical mechanism reinforcing social bonds between humans.

Short Title: NeuroImage