Using data on the genetic basis of depression and happiness, scientists think we can change how our brain responds to good and bad news.
But she also writes that “subtle variation in how we see the world -- our biases and quirks of mind -- can reshape the actual architecture of our brain, pushing us toward a more optimistic or pessimistic take on life. By changing the way our brain responds to challenges and joys, we can change the way we are.”
In other words, nature and nurture.
To explain how neither genes nor environmental events alone are enough to predict depression risks, she cites a study looking at whether people with the short version of the serotonin transporter gene would be at high risk of depression.
That study found that those with the short version of the gene didn’t seem to have any higher risk of depression, but when they experienced 3 or more really negative life events, their risk was far, far higher. On the other hand, people with the longer version of the same gene who also had three or more very adverse life events didn’t have a higher risk of depression.
In her current work, Fox uses functional magnetic resonance imaging (fMRI), which displays brain activity by following the flow of blood. She’s looking into the fundamental biases that underlie what she’s describing as our ‘rainy brain’ or ‘sunny brain’ circuits.
On the one hand we have the ‘rainy brain’ -- the system underlying a more pessimistic attitude or an anxious kind of personality style:
Now, in ancient times, that was there to alert us to predators. Nowadays most of us aren’t, you know, worried too much about predators, but now there’s lots of other things to worry about. So we need a functioning fear system. Now, what happens over time is that nerves and fibers link up that ancient amygdala, the fear system, with areas in the frontal cortex, the more recent areas of our brain in evolutionary terms… So that while the amygdala might fire and say, “There’s danger here, we’d better run,” the higher areas in the cortex will tend to dampen things down and put on the brake a little bit.
That’s the same kind of mechanism working in the ‘sunny brain’ side of things:
So, again, we have a very ancient system called the nucleus accumbens, which is the pleasure system. Again, it’s an old system in the brain which basically pulls us toward the things that are good for us. So things like warmth, food, shelter, sex, all of those things that are good for either us as individuals or for our species, and the nucleus accumbens tends to underlie all of that. And just as in the rainy brain system, the nucleus accumbens links up to areas in the prefrontal cortex.
Specifically, her team uses computers to flash up pairs of images -- “say a very nasty image and a very positive image” -- and then people are asked to search for a target like a yellow square or a blue triangle.
When the target appears near the location of, say, a nasty image, we find that people are a little bit faster. So people who are more pessimistic or more prone to anxiety will be just a little bit quicker in detecting that target if it appears near a nasty image. Whereas if the target is appearing more near a positive, a very nice image, we find that more optimistic, upbeat people tend to zone in there.
“So whatever’s going on around us, it’s what our brain tunes into automatically and how we interpret situations that really makes a difference,” she says.
She adds: "We’re effectively training our brain, if you’d like. If we start off with a slight tendency to interpret something in a negative way, over time we’re actually training our brain more and more and more to develop that kind of mind-set... this really flows down to the subliminal biases and even to actual brain circuits."
[From IEEE Spectrum]
Image: Elaine Fox