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The new finding is described in this week's issue of the Proceedings of the National Academy of Sciences ( PNAS ). The team measured brain activation while self-identifiedheterosexual male subjects lay in a functional MRI scanner and wereeach caressed on the leg under two different conditions. In thefirst condition, they saw a video of an attractive female bendingdown to caress them; in the second, they saw a video of a masculineman doing the same thing. The men reported the experience aspleasurable when they thought the touch came from the woman, andaversive when they thought it came from the man. And their brainsbacked them up: this difference in experience was reflected in theactivity measured in each man's primary somatosensory cortex. "We demonstrated for the first time that the primarysomatosensory cortex -- the brain region encoding basic touchproperties such as how rough or smooth an object is -- also issensitive to the social meaning of a touch," explains MichaelSpezio, a visiting associate at Caltech who is also an assistantprofessor of psychology at Scripps College in Claremont,California. "It was generally thought that there are separatebrain pathways for how we process the physical aspects of touch onthe skin and for how we interpret that touch emotionally -- thatis, whether we feel it as pleasant, unpleasant, desired, orrepulsive. Our study shows that, to the contrary, emotion isinvolved at the primary stages of social touch." Unbeknownst to the subjects, the actual touches on their leg werealways exactly the same -- and always from a woman. Yet, it feltdifferent to them when they believed a man versus a woman was doingthe touching. "The primary somatosensory cortex responded more to the'female' touch than to the 'male' touch condition, even whilesubjects were only viewing a video showing a person approach theirleg," says Ralph Adolphs, Bren Professor of Psychology andNeuroscience at Caltech and director of the Caltech Brain ImagingCenter, where the research was done. "We see responses in apart of the brain thought to process only basic touch that wereelicited entirely by the emotional significance of social touchprior to the touch itself, simply in anticipation of the caressthat our participants would receive." The study was carried out in collaboration with thehusband-and-wife team of Valeria Gazzola and Christian Keysers, whowere visiting Caltech from the University of Groningen in theNetherlands. "Intuitively, we all believe that when we are touched bysomeone, we first objectively perceive the physical properties ofthe touch -- its speed, its gentleness, the roughness of theskin," says Gazzola. "Only thereafter, in a separablesecond step based on who touched us, do we believe we value thistouch more or less." The experiment showed that this two-step vision is incorrect, atleast in terms of separation between brain regions, she says, andwho we believe is touching us distorts even the supposedlyobjective representation of what the touch was like on the skin. "Nothing in our brain is truly objective," adds Keysers."Our perception is deeply and pervasively shaped by how wefeel about the things we perceive." One possible practical implication of the work is to help reshapesocial responses to touch in people with autism. "Now that we have clear evidence that primary somatosensorycortex encodes emotional significance of touch, it may be possibleto work with early sensory pathways to help children with autismrespond more positively to the gentle touch of their parents andsiblings," says Spezio. The work also suggests that it may be possible to use film clips orvirtual reality to reestablish positive responses to gentle touchin victims of sexual and physical abuse, and torture. Next, the researchers hope to test whether the effect is as robustin women as in men, and in both sexes across sexual orientation.They also plan to explore how these sensory pathways might developin infants or children. We are high quality suppliers, our products such as China Carbon Steel Boiler Tube , Carbon Steel Seamless Pipe for oversee buyer. To know more, please visits Carbon Steel Seamless Pipe.
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