You might expect a gentle touch on the shoulder or a caress of the cheek to invoke feelings of compassion and love. But there are times where a touch like that might not be so pleasant. A new study has found, in fact, that the brain may respond to a sensual caress with great aversion, shedding light on the role it plays in our response to social touch.
How did they do the study?
Neuroscientists from California’s Institute of Technology, along with Valeria Gazzola and Christian Keysers from the University of Groningen in the Netherlands conducted this study to analyze how the brain processes touch into emotion. Using an MRI scanner, researchers recorded the brain activity of heterosexual male participants as they watched two different videos while being caressed on the leg by an unseen research assistant. The first video depicted an attractive woman bending down to caress them; the second video was of a man doing the same.
What did they find?
Not surprisingly, the participants reported a pleasurable experience when they associated the sensation of the leg caress with the attractive woman on the screen, and a highly negative experience being caressed while the man on screen appeared to be doing the caressing. And their responses were consistent with the activity shown in the somatosensory cortices of their brains as shown on their fMRI scans. But, for the first time, an emotional response to touch was observed in the primary somatosensory cortex region of the brain, which is usually associated with recognizing the physical feeling of touch. This suggests that our somatosensory cortices not only recognize how a physical touch feels in pressure and gentleness, but they also play a role in processing the emotional--pleasant or repulsive--response to the touch. What the participants didn’t realize was that, in reality, the physical caress was always provided by a woman.
So what’s the significance?
While more research is needed to confirm these results in homosexual men and women of all sexual orientations, the findings suggest that it may be possible to use video or virtual reality technology to reprogram positive responses to intimate touch in sexual and physical abuse victims. Researchers also hope to explore the finding further to see if there are sensory pathways that may help reshape social responses to touch in children with autism spectrum disorders.
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