Primary somatosensory cortex discriminates affective significance in social touch
- aDepartment of Neuroscience, University Medical Center Groningen, 9713 AW Groningen, The Netherlands;
- bSocial Brain Laboratory, The Netherlands Institute for Neuroscience, Royal Netherlands Academy for the Arts and Sciences, 1105 BA Amsterdam, The Netherlands;
- cDepartment of Psychology, Scripps College, Claremont, CA 91711;
- dDivision of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA 91125;
- eCognition Psychology Neuroscience Laboratory, University of Pavia, 27100 Pavia, Italy; and
- fComputation and Neural Systems Program, California Institute of Technology, Pasadena, CA 91125
See allHide authors and affiliations
Edited by Riitta Hari, School of Science, Aalto University, Espoo, Finland, and approved April 24, 2012 (received for review August 11, 2011)

Abstract
Another person’s caress is one of the most powerful of all emotional social signals. How much the primary somatosensory cortices (SIs) participate in processing the pleasantness of such social touch remains unclear. Although ample empirical evidence supports the role of the insula in affective processing of touch, here we argue that SI might be more involved in affective processing than previously thought by showing that the response in SI to a sensual caress is modified by the perceived sex of the caresser. In a functional MRI study, we manipulated the perceived affective quality of a caress independently of the sensory properties at the skin: heterosexual males believed they were sensually caressed by either a man or woman, although the caress was in fact invariantly delivered by a female blind to condition type. Independent analyses showed that SI encoded, and was modulated by, the visual sex of the caress, and that this effect is unlikely to originate from the insula. This suggests that current models may underestimate the role played by SI in the affective processing of social touch.
Footnotes
↵1V.G. and M.L.S. contributed equally to this work.
- ↵2To whom correspondence may be addressed. E-mail: radolphs{at}hss.caltech.edu or c.keysers{at}nin.knaw.nl.
Author contributions: V.G., M.L.S., F.C., R.A., and C.K. designed research; V.G., M.L.S., F.C., and C.K. performed research; V.G., M.L.S., J.A.E., and C.K. analyzed data; and V.G., M.L.S., R.A., and C.K. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
See Author Summary on page 9688 (volume 109, number 25).
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1113211109/-/DCSupplemental.
Freely available online through the PNAS open access option.
Citation Manager Formats
Article Classifications
- Biological Sciences
- Neuroscience