Does the whole world seem a little more in-focus in times of intense pleasure or pain? You could be a carrier of a particular gene variant that literally makes certain people see emotional images more clearly, according to research from the University of British Columbia recently published in The Journal of Neuroscience.
The specific gene is a deletion variant of ADRA2b, which means that it is missing a few links in the DNA chain compared with the standard copy. About half of Canadians are estimated to carry it. People with this variant are more attuned to emotional information in the same sort of way that artists have a heightened sense for visual aspects of the world, said UBC psychologist and lead author Rebecca Todd.
"Visual artists in particular are very, very sensitive to colour and contrast and light and the relevance of visual things. I kind of think of deletion carriers as being very sort of artist-like, in their perception of the emotional shades around them," said Todd. By contrast, she describes herself as "a boring non-deletion carrier" who just doesn't pay as much attention to emotional aspects of the world.
The study took 39 Caucasian University of Toronto undergraduate students and subjected them to a brain scan while they looked at positive, negative and neutral images. Twenty one were carriers of the deletion variant.
Negative images included things like "scary snakes and mutilated people; a baby with a tumour on its eye that's very distressing," said Todd. An example of a neutral image might be someone standing next to a car or riding an escalator. Positive images were harder to come by, especially since the intention was for them to be as dramatically positive as the negative images were negative. "There was a lot of very dated 1980s erotica," she said, laughing.
All of the images were overlaid with a certain amount of visual noise, which basically looks like static on an old television set. The task for participants was to estimate the noisiness of a given image compared with a version of the same image that was digitally scrambled so it would be similar in visual content but void of emotional meaning.
The trend for all people is to see less static on images with positive or negative content, an effect that scientists describe as emotionally enhanced vividness. But for those with the gene variant, this perceived clarity is much, much stronger. Their brain scans also showed a lot more activity in the areas that regulate emotions and interpret pleasure and threats. "It was a very, very strong finding," said Todd. It's rare for a study on a gene's behavioural effects to show such strong correlation with such a small sample size, she said.
The research could help explain why some people are more susceptible to post traumatic stress disorder after a distressing event. "I'm really excited about looking at how this genetic difference, in interaction with other genes and experience, influences emotional learning," said Todd. She plans to further study whether or not being a carrier of the gene variant might predispose someone to anxiety or addiction. "If you learn the positive value of a drug more quickly, are you more vulnerable to becoming addicted to it?" she asked.
It's not all bad news for carriers of the gene, though. Those of us who are more sensitive are also better at separating important information from all the benign data that we're bombarded with in our daily lives. Positive stimuli come in more strongly and are more easily remembered, too, according to Todd.
The prevalence of the variant can range quite a bit between ethnic groups, which is not uncommon. While Caucasians are estimated to have a prevalence rate over 50 percent, one study of Rwandans found the deletion variant in just 10 per cent of the population.
The ADRA2b deletion variant is a very good predictor that someone will perceive emotionally enhanced vividness, but no single gene can be a prescription for a certain behaviour or experience, said Todd. Like everything in the jumble of neurons that make up our brain, how we see the world is shaped by a complicated interaction of many different genes on top of memory and lived experience.