Molecular tag explains differences in brain's response to anger, fear

fear
Credit: George Hodan/public domain

When people perceive anger and fear in others, a region of the brain called the amygdala sends signals throughout the rest of the brain that allow us to prepare for potentially threatening situations.

Interestingly, people differ in the way that their responds to these cues. For example, some people may over-respond to relatively non-threatening signals, which may be an inefficient use of costly bioenergetic resources.

Researchers at the University of Virginia have now uncovered a chemical tag on DNA that can be drawn from the blood and used to understand these differences. Their findings are reported online this week in the Proceedings of the National Academy of Sciences Early Edition.

The chemical tag - called DNA methylation - is found on the oxytocin receptor gene. This receptor is important for allowing the cell to respond to a molecule called oxytocin. Oxytocin, sometimes called the "love hormone," is linked to a variety of human behaviors - relationship forming, caring, bonding and trust, among others. In short, the hormone is important in regulating the way we socialize and respond to kindness or threats. Individuals low in DNA methylation on the oxytocin receptor may be better able to utilize this important hormone.

Using a study sample of 98 healthy Caucasians aged 18 to 30 who provided blood samples and underwent functional MRI brain scans while looking at pictures of angry and fearful faces, the researchers identified a relationship between the level of DNA methylation in an individual and activity in the amygdala and other parts of the brain responsible for emotion processing.

According to study co-author James P. Morris, a U.Va. assistant professor of psychology, individuals with lower DNA methylation show diminished brain response to angry and fearful faces and greater communication between brain regions important for regulating emotion.

The research team hypothesizes that this may be important for understanding the state of the disrupted or diseased brain as individuals with autism spectrum disorder, psychopathy, depression and anorexia nervosa all display high degrees of DNA methylation at the oxytocin receptor.

"Defining biomarkers like this epigenetic tag associated with the may help us to predict future social developmental problems and inform interventions for those with social deficits," said co-author Jessica J. Connelly, a U.Va. assistant professor of psychology.

"While our findings certainly have clinical implications, we show that even in a healthy population these markers are variable and may partially explain what makes each of us unique in how we respond in social situations," said the study's lead author Meghan Puglia, a Ph.D. candidate in psychology at U.Va.

The investigators believe it is possible that eventually a blood test could be developed that would, in effect, predict how a person would behave in various social situations. Connelly and her colleagues are sorting through the complexities of epigenetics - the nature -and-nurture question of how both genetics and environment affect psychological development.


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More information: Epigenetic modification of the oxytocin receptor gene influences the perception of anger and fear in the human brain, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1422096112
Citation: Molecular tag explains differences in brain's response to anger, fear (2015, February 9) retrieved 22 August 2019 from https://medicalxpress.com/news/2015-02-molecular-tag-differences-brain-response.html
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JVK
Feb 09, 2015
The obvious link from the epigenetic landscape to the physical landscape of DNA in organized genomes also links hormones, such as oxytocin, during the development of behavior.

It is the link from olfaction and pheromones to receptor mediated feedback loops that link nutrient uptake from metabolic networks to genetic networks and to the physiology of reproduction.

For a review of RNA-directed DNA methylation and RNA-mediated hormone-organized and hormone-activated behaviors, see From Fertilization to Adult Sexual Behavior http://www.hawaii...ion.html

For an extension across species of what is known about the biophysically constrained chemistry of protein folding to RNA-directed DNA methylation and RNA-mediated amino acid substitutions that differentiate all cell types in all individuals of all species, see Nutrient-dependent/pheromone-controlled adaptive evolution: a model. http://www.ncbi.n...24693353

Feb 10, 2015
If you fear predictability in the wrong hands, then I will join you.
If you do not fear predictability, then I will join you.

The investigators believe it is possible that eventually a blood test could be developed that would, in effect, predict how a person would behave in various social situations.


A drone society will eradicate evolution.
You are not predestined to eat or smell anything. Despite predisposition.


JVK
Feb 14, 2015
What is currently known about the molecular epigenetics of transgenerational epigenetic inheritance clearly shows that we are genetically predisposed to respond to the food odors and pheromones that the offspring of all parents typically encounter. Our encounters are due to similarities in the epigenetic landscape that help to ensure the physical landscape of DNA in the organized genomes of species from microbes to man is organized by experience.

That fact makes it difficult to interpret the comment by "russell_russell"

It is not placed into the context of anything currently known about physics, chemistry, or molecular biology. It is placed into the context of the automagical evolution of a "drone society."

The only way I know to make sense of "drone societies" is in the context of the honeybee model organism. It is clear that behavior is nutrient-dependent RNA-mediated and pheromone-controlled. If not, the model organism would not exist.

Mar 16, 2015
In my view, the next step is to develop evidence for how the oxytocin receptor gene became methylated.

The subjects had a wide range of DNA methylation at the studied gene site – from 33% to 72% methylated!

Why?

At the same gene site: "There was a significant effect of sex such that females have a higher level of methylation than males."

Why?

Why act as if the likely factors that cause epigenetic DNA methylation are off-limits when asking questions of the subjects?

Why not consider an approach that studies that show that early emotional experiences change our brains use, like the Childhood Trauma Questionnaire and Adverse Childhood Experience study?

Wouldn't research on the subjects' histories help a great number of other humans?

http://surfaceyou...ealself/

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