Social touch modulates endogenous μ-opioid system activity in humans

Lauri Nummenmaa*, Lauri Tuominen, Robin Dunbar, Jussi Hirvonen, Sandra Manninen, Eveliina Arponen, Anna Machin, Riitta Hari, Iiro P. Jääskeläinen, Mikko Sams

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

63 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)242-247
Number of pages6
Publication statusPublished - 1 Sep 2016
MoE publication typeA1 Journal article-refereed


  • Bonding
  • Opioids
  • PET
  • Somatosensory
  • Touching

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