Morning Lecture guest column: With dopamine, troughs just as important as surges

Guest column by Marina R. Picciotto. Picciotto will give Thursday’s Morning Lecture in the Amphitheater at 10:45 a.m. Check out the preview for the lecture.

We all know what happiness is. Even us curmudgeons can think back to a moment of quiet satisfaction when we looked around and thought, “This is good.”

One autumn morning as a child, I was walking the three blocks to elementary school. There were no other kids around (I was either early or late to class), and the red and orange leaves were scattered on the sidewalk, practically asking to be kicked around. The sky was as clear as the light in an Edward Hopper painting. I shuffled along, looking up at the few white clouds on the still-warm fall morning and thought, “It is good to be alive.”

Every once in a while I recapture that feeling, if only for a moment. I hold on to it as long as I can.

Philosophers have offered many explanations of happiness. As a neurobiologist, I’m most satisfied when philosophy is anchored in an understanding of brain function. We can look to neurobiology to understand basic brain states associated with pleasure, though happiness is a bit more complex.

Sometimes, structures or molecules in the brain work in multiple functions. This is certainly the case for dopamine. These days, dopamine has become the “rock star” neurotransmitter. Non-neuroscientists invoke dopamine when they talk about pleasure, and the press finds the idea of dopamine familiar enough to put it in headlines and stories completely unrelated to health. You can even Google dopamine and find entries that read “dopamine, the pleasure hormone.”

But many people don’t realize that dopamine is actually a very complicated molecule. We need dopamine to experience aversive events as well as pleasurable ones. The peaks and dips in dopamine levels turn out to be more important for matching our expectation to our environment than for just experiencing a rush of pleasure. Changes in dopamine signal that our expectations are out of whack, or that we need to alter our behavior as a result of new information or new experiences.

What does it mean that the “pleasure hormone” is really a signal that we have just experienced something we should learn from? First, it says that learning and pleasure are intimately intertwined, and that we should remember this when we sit children down in a classroom. Second, it tells us that both pleasure and pain come from a mismatch between what we expect and what we experience. This also tells us that the balance between expectation and experience could be an important key to understanding happiness.

The first delicious chocolate truffle from an otherwise nondescript box is most exceptional the first time, as it is unexpected. This can also be true in understanding drug addiction. Crack cocaine abusers often report that their first experience was monumental, and that every time they subsequently used they were chasing that first high.

The surges of dopamine that come with unexpected rewards don’t match our understanding of happiness.

Instead, the smoothing of the dopamine curve that occurs when our previous experiences predict the correct rewarding outcome maps beautifully onto the satisfaction of a life lived in harmony with reasonable expectation. If this is so, one of the biggest barriers to happiness may be the overwhelming richness of possibility we are confronted with by a society in which raising expectation is essential to maintaining us as consumers. Surges in dopamine come from unexpected rewards, but troughs come from mismatched expectations. Therefore, happiness may be that elegantly balanced state in which we ride on a contented wave of matched expectation and experience.

Marina R. Picciotto is the Charles B.G. Murphy Professor in Psychiatry and professor of neurobiology and pharmacology at Yale University.