The touch of another human being can raise levels of the "feel good" hormone oxytocin. But the context plays a big role. The situation not only affects the oxytocin level in the moment, but also later, researchers at Linköping University and the University of Skövde show. The study is published in the journal eLife.
An embrace from a parent, a warm hand on the shoulder or a pleasant caress from a romantic partner are examples of how touch can strengthen social bonds between people and affect emotions. But even if touch and the sense of touch have a very important function, there is a lack of knowledge about how it works.
Studies performed on animals have shown that the hormone oxytocin is linked to touch and social attachment. But there are many unanswered questions about what role oxytocin plays in social interaction and how this hormone works together with the brain. To study this more closely, researchers at Linköping University and the University of Skövde have investigated what happens in the human body during skin-to-skin contact.
“We saw that the body's oxytocin response to touch is affected by the situation: what has happened a while before and who you are interacting with. The hormone does not act like a switch that is turned on and off, but rather like a dimmer,” says India Morrison, Senior Associate Professor at the Department of Biomedical and Clinical Sciences at Linköping University.
Measured the relationship between hormones and brain activity
In the study, which was published in the journal eLife, 42 women participated. The experiment itself consisted of the woman's male partner stroking her arm with his hand. Meanwhile, the activity in her brain was visualised with functional magnetic resonance imaging, fMRI.
During the experiment, the researchers also took repeated blood samples to monitor whether the level of oxytocin in the woman's blood changed over time. By combining the different measurements, the researchers were able to investigate whether there was a connection between the hormonal and brain responses to social touch in humans.
The measurements from the social interaction between the woman and her partner were compared to what happened when instead it was a strange, non-threatening man who touched the woman's arm in the same way. In half of the experiments it was the partner who stroked her arm first, and in half it was the stranger. The women who participated were informed about who was touching their arm.
“Our basic question was whether the oxytocin level would be higher when the partner touched the woman's arm than when a stranger did. The answer was yes - but only when her partner was first in the order,” says Linda Handlin, Lecturer in Biomedicine at the University of Skövde.
The partner's touch increases oxytocin levels
The researchers found that when the partner was first, the woman's oxytocin level increased during the social interaction, then decreased and increased again when the stranger did the same. If, on the other hand, it was the stranger who touched her first, nothing happened to the oxytocin at all. When the partner then stroked her arm, there was only a small increase in oxytocin. The changes in oxytocin levels were linked to activity in areas of the brain that are important for putting events into context.
Oxytocin is released in a variety of situations and has several functions in the human body.
“It can be good to keep in mind that the context is important, for example when it comes to giving synthetic oxytocin as a nasal spray as part of treatment for conditions that affect mood,” says India Morrison.
The research has been financed by the Swedish Research Council.
Read the article
Read the article: Human endogenous oxytocin and its neural correlates show adaptive responses to social touch based on recent social context, Linda Handlin, Giovanni Novembre, Heléne Lindholm, Robin Kämpe, Elisabeth Paul och India Morrison, (2023), eLife, publicerad online den 9 maj 2023, doi: https://doi.org/10.7554/eLife.81197