Summary: Silencing a gene responsible for the production of oxytocin can affect a person’s ability to form healthy relationships and recognize the emotional states of others, a new study reports.
Source: University of Georgia.
A team of researchers led by psychologists at the University of Georgia have found that the silencing of a specific gene may affect human social behavior, including a person’s ability to form healthy relationships or to recognize the emotional states of others.
In a paper published June 20 in the Proceedings of the National Academy of Sciences, scientists examined how a process known as methylation, which can reduce the expression of specific genes, affects a gene called OXT. This gene is responsible for the production of a hormone called oxytocin, which is linked to a wide range of social behaviors in humans and other mammals.
“Methylation restricts how much a gene is expressed,” said Brian W. Haas, the study’s lead author and assistant professor of psychology in UGA’s Franklin College of Arts and Sciences. “An increase in methylation typically corresponds to a decrease in the expression of a gene, so it affects how much a particular gene is functioning.
“When methylation increases on the OXT gene, this may correspond to a reduction in this gene’s activity. Our study shows that this can have a profound impact on social behaviors.”
Haas and his collaborators collected saliva samples from more than 120 study participants to perform genetic tests that show the levels of methylation on the OXT gene. The participants went through a battery of tests to evaluate their social skills as well as their brain structure and function.
What they found is that participants with greater methylation of the OXT gene—likely corresponding to lower levels of OXT expression—had more difficulty recognizing emotional facial expressions, and they tended to have more anxiety about their relationships with loved ones.
In one part of the study, participants were presented with brief video clips of people’s faces that begin with a neutral expression and gradually morph into an emotional face. The participant’s job is to press a button as soon as they feel confident that they know which type of emotion that face is showing.
“Participants with greater methylation of the OXT gene were less accurate in describing the emotional states of the people they saw in pictures,” he said. “That’s a typical characteristic associated with autism, for example.”
The researchers also used functional magnetic resonance imaging—a technology that measures brain activity by detecting changes in oxygenated blood flow—to examine the regions of people’s brains that were activated during various tasks, and they found that those with increased methylation of the OXT gene had reduced neural activity in brain regions associated with social-cognitive processing.
These participants also displayed reduced gray matter within an area of the brain called the fusiform gyrus, which is important for face processing and social cognition.
“All of our tests indicate that the OXT gene plays an important role in social behavior and brain function,” Haas said.
While Haas and his co-authors caution that these results are preliminary and that much work must be done to more clearly define the role of oxytocin and the genes that control it, he is hopeful this research may one day lead to new and improved treatments for a variety of social disorders.
“Methylation is a dynamic process, and level of methylation can change over the course of a person’s lifetime,” he said. “But it may be possible to alter the level of methylation with some type of medication that could help people who have abnormalities in social cognition.”
Additional researchers on the project include UGA graduate students Nick Cochran and Megan M. Filkowski; Lydia Denison, Shota Nishitani and Alicia K. Smith, Emory University; and Alexandra Ishak, Stanford University School of Medicine.
Source: Stephanie Schupska – University of Georgia
Image Source: This NeuroscienceNews.com image is in the public domain.
Original Research: Abstract for “Epigenetic modification of OXT and human sociability” by Brian W. Haas, Megan M. Filkowski, R. Nick Cochran, Lydia Denison, Alexandra Ishak, Shota Nishitani, and Alicia K. Smith in PNAS. Published online June 20 2016 doi:10.1073/pnas.1602809113
Epigenetic modification of OXT and human sociability
Across many mammalian species there exist genetic and biological systems that facilitate the tendency to be social. Oxytocin is a neuropeptide involved in social-approach behaviors in humans and others mammals. Although there exists a large, mounting body of evidence showing that oxytocin signaling genes are associated with human sociability, very little is currently known regarding the way the structural gene for oxytocin (OXT) confers individual differences in human sociability. In this study, we undertook a comprehensive approach to investigate the association between epigenetic modification of OXT via DNA methylation, and overt measures of social processing, including self-report, behavior, and brain function and structure. Genetic data were collected via saliva samples and analyzed to target and quantify DNA methylation across the promoter region of OXT. We observed a consistent pattern of results across sociability measures. People that exhibit lower OXT DNA methylation (presumably linked to higher OXT expression) display more secure attachment styles, improved ability to recognize emotional facial expressions, greater superior temporal sulcus activity during two social-cognitive functional MRI tasks, and larger fusiform gyrus gray matter volume than people that exhibit higher OXT DNA methylation. These findings provide empirical evidence that epigenetic modification of OXT is linked to several overt measures of sociability in humans and serve to advance progress in translational social neuroscience research toward a better understanding of the evolutionary and genetic basis of normal and abnormal human sociability.
“Epigenetic modification of OXT and human sociability” by Brian W. Haas, Megan M. Filkowski, R. Nick Cochran, Lydia Denison, Alexandra Ishak, Shota Nishitani, and Alicia K. Smith in PNAS. Published online June 20 2016 doi:10.1073/pnas.1602809113