April 1, 2013 | 16
NOTE: April Fool’s always catches me completely by surprise, and I’m really terrible at practical jokes anyway. So today’s post is not a joke. Real study. Really.
Welcome to Lake Wobegon, where all the women are strong, all the men are good-looking, and all the children are above average.
Much as we all like to think we’re modest, most of us really aren’t. We might try to be humble and say “we’re just some guy, you know?“, but most often, we actually think we’re better than average. Maybe we think we’re smarter, or better looking, or nicer, or maybe even all of the above.
And it turns out that thinking we’re above average (even though, statistically, only half of us CAN be above average) is actually good for us. People who suffer from depression usually show a symptom called “depressive realism”. They actually see themselves MORE REALISTICALLY than other people do. And seeing yourself in the harsh light of reality…well it’s pretty depressing (you don’t really want to know how average you are in a sea of over 6 billion people. You don’t). Thinking that you are better than you actually are is sometimes called the Dunning-Kruger effect (though that usually refers specifically to how competent you think you are…when really you’re not), but in psychology it’s called the Superiority Illusion: the belief that you are better than average in any particular metric.
But where does the superiority illusion come from? How do our brains give us this optimism bias?
Yamada et al. “Superiority illusion arises from resting-state brain networks modulated by dopamine” PNAS, 2013.
The authors of this study wanted to look at how our brain might give us the idea that we are better than the other guy. They were particularly interested in the connection between two areas of the brain, the frontal cortex, and the striatum. The frontal cortex does a lot of higher processing (things like sense of self), while the striatum is involved in things like feelings of reward. The connection between these two areas is called the fronto-striatal circuit. And the strength of that connection may mean something for how you think of yourself. While people who think well of themselves have relatively low connectivity in this circuit, people with depression have higher levels of connectivity. The two areas are MORE connected.
And the authors were also interested in the neurotransmitter dopamine. Dopamine is a particularly important chemical in things like reward processing, attention, and the expectation of pleasurable sensations. But the actual actions of dopamine depend heavily on the receptors that it hits. If it hits dopamine D1-type receptors, for example, it will often stimulate cells to fire. If it hit dopamine D2-type receptors, it will inhibit cells from firing.
And how many of each type of receptor that you have in certain areas can change how you think of yourself. For example, people with fewer D2 receptors in the striatum (associated with things like reward, etc), think better of themselves, than people who have high amounts of D2 receptors in the same area.
The authors wanted to know how these two things, the fronto-striatal circuit and dopamine receptors, related to how people think of themselves. They took a group of normal volunteers, all of whom had something of the superiority illusion. Then they gave them both an fMRI test and a PET scan. The fMRI was to look at the level of connectivity in the fronto-striatal circuit, while the PET scan used radioligand bound dopamine receptor agonists to look at the concentrations of D2 receptors in the striatum.
They showed that the amount of conntectivity in the fronto-striatal circuit was inversely related to how people viewed themselves. The more connectivity, the less people suffered from the superiority illusion.
The authors also showed that the decreased connectivity in the fronto-striatal circuit was correlated with decreased D2 receptor binding. So low connectivity and low binding are associated with a pretty good view of yourself. The authors think that the dopamine in the striatum acts on the D2 receptors to decrease the connectivity in the fronto-striatal circuit, resulting in a better view of yourself. So the more dopamine you have, the bigger of a decrease in connectivity, and the better the view of yourself. Conversely, the less dopamine, the less inhibition and a stronger connection, and the more realistic your appraisal of your own averageness.
Keep in mind, though, this is fMRI data, though it is also strengthened with PET imaging. fMRI data looks at the relative activity of some areas of the brain compared to others during a task (so, say, for a self-evaluation task, the control might be the cerebellum, which presumably doesn’t have much meaningful activity to be doing during self-evaluation). But because you are comparing activity in only one or two regions with activity in a reference (looking at the activity from fMRI in ALL areas of the brain would be a monumental task), you tend to pick areas that you are pretty sure are going to show activity correlated with what you’re looking for. In other words, there are few surprises with fMRI, you generally find what you expect to find.
In addition, even with the addition of the PET imaging for the dopamine receptors, this activity is still only correlative. So you can say that the activity in these circuits and the dopamine measures are correlated with people’s feelings of their own superiority, but you can’t REALLY say that the lower connectivity here is what gives people the feeling they are above average. In order to do that, you would have to be able to specifically stimulate say, the dopamine system, or the connectivity the frontal cortex and the striatum. You could actually probably do this with a D2 receptor agonist, though getting it just in the striatum would be a difficult thing. If someone then thinks they are totally better than everyone else (or, say, a depressed person suddenly feels much better about themselves), you might be able to say that this connection and the dopaminergic activity in it DETERMINES whether you think you’re better than other people. Right now? It’s correlated, and they did a model. But they didn’t do the actual test. It could be the upstream precursor higher processes, or the downstream effect of “lower” processes like those in the limbic system. You can’t really say for certain.
But it does pose an interesting idea for how to deal with people with depression. People with depression often feel worthless, or that they just aren’t as bright or talented as they actually are. Other studies have shown that people with depression can have hyperconnectivity in the fronto-striatal circuit. We saw in this study that LESS connectivity is correlated with thinking you’re above average. So, IF the hyperconnectivity is the CAUSE of feeling you’re not as great, it might be possible to dampen the activity in that circuit, and maybe make people feel better about themselves. But that’s a lot of ifs. You’d have to be make sure that was the case, you’d have to be able to specifically target the activity of this circuit, and you’d have to be sure that the feelings of worthlessness that people with depression feel are the most important problem that they have. As is it, and as the authors themselves note, the symptom of feeling worthless, and the underlying neurobiology, are probably part of a large interconnected system that has many differences during depression. So I don’t think it’s something that we will be using any time soon. But the idea of connections and feelings of self-worth is still an interesting one to think about.
Yamada, M., Uddin, L., Takahashi, H., Kimura, Y., Takahata, K., Kousa, R., Ikoma, Y., Eguchi, Y., Takano, H., Ito, H., Higuchi, M., & Suhara, T. (2013). Superiority illusion arises from resting-state brain networks modulated by dopamine Proceedings of the National Academy of Sciences, 110 (11), 4363-4367 DOI: 10.1073/pnas.1221681110