A gene called OPRM1 governs the production of the body's natural pain-killers, mu-opioid receptors. People with a rare variation of this gene are more sensitive to pain and researchers at the University of California, Los Angeles have found that they may be more sensitive to social rejection as well. The researchers collected saliva samples from 122 volunteers to see which variation of the gene they had. They then gave them a questionnaire to measure their sensitivity to social rejection. Finally the participants took part in a computer game with other people which - unbeknown to them - was deliberately designed to exclude them. As they were experiencing this exclusion their brains were scanned to see which areas were most active. The study found that people with the 'sensitive' variant of OPRM1 were also more sensitive to social rejection and showed greater activity in their dorsal anterior cingulate cortex and anterior insula in response to social exclusion.
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