Lovebirds—How Dopamine Helps Zebra Finches Fall in Love and Stay in Love

The concept of love has fascinated Homo sapiens since we first started experiencing those warm mushy feelings. Ever since then, painters and writers and actors have found avenues to express the ways that love makes them feel. Now, scientists are discovering what happens in the brain that creates the compulsion for monogamy that many believe Hallmark cards tricked us into thinking we needed. For my project, I am studying the changes in the brains of zebra finches that lead to monogamy. Of course, what we know as “love” has been socially constructed by humans, so technically I am studying what scientists call “pair-bonding” in monogamous birds. Research in voles, another monogamous species, has shown that there are increases of dopamine receptors in the part of the brain associated with rewards when voles have been pair-bonded for long amounts of time. Dopamine receptors bind dopamine—a neurotransmitter responsible for many feelings and movements, including pleasure—and send messages to other parts of the brain—for example, “This candy is delicious, let’s keep eating it!” or “I am in love with this other bird, let’s see if she is interested in mating!” Specifically, the number of dopamine 1 receptors increased the longer that voles were paired, and activation of these receptors also caused males to be disinterested in females that weren’t their mate—and dopamine 2 receptors increased when the pair-bonding was first happening (Aragona et al., 2006). Basically, the activation of dopamine 2 receptors caused the voles to “fall in love,” and the dopamine 1 receptor activation maintained the love over time. This connects to zebra finches because my PI, Dr. Coleman, has shown that by using chemicals that activate the dopamine 2 receptors manually, a scientist can induce partner-preference in zebra finches—sort of like a “love potion,” that makes zebra finches “fall in love”! The same method was also performed in Aragona et al.’s 2006 paper, where partner preference was induced in voles. This research is one of the final pieces in Dr. Coleman’s project about the mating preferences of zebra finches. You might be wondering—who cares about the love lives of zebra finches? I can name one famous person you might recognize who would be very interested in this research: Charles Darwin. This research furthers Darwin’s theories of sexual selection—what traits are sexually attractive, and should be passed down? How does the brain “fall in love”—in other words, how does the brain select a mate, one of the most important decisions in any organism’s life, especially if the organism is monogamous? Our preliminary results do not indicate an increase in neither dopamine 1 nor dopamine 2 receptors in paired birds compared to sexually naïve birds. Instead, we are seeing an increase in the enzyme tyrosine hydroxylase, which helps make dopamine. This result suggests that, in zebra finches, there may not be a change in the number of receptors, but instead just an increase of the neurotransmitter itself. We plan on continuing the experiment, and looking in several parts of the brain to see if there is an increase in a different area.

“The important thing to remember is that you have a goal, and that small hiccups shouldn’t dissuade you from research and making discoveries.”

Like Darwin, I will never just wake up one day and have all the answers to all the questions of the universe, much less innate knowledge of all techniques that I will need. For example, this summer, my lab has been collaborating with the lab of Dr. Stephanie White, specifically with her postdoc, Dr. Nancy Day at UCLA. We have been utilizing Dr. Day’s expertise in quantitative real-time PCR (qPCR). This is a technique used by scientists for many reasons, but in our case we will use qPCR to analyze dopamine 1 and dopamine 2 receptor gene expression in finch brains. This is one of the realities of research I learned this summer: rarely will there always be in your lab (or department) the materials or people who can do everything that you need to do, and sometimes you need to rely on your friends and colleagues (hopefully made by networking) and their expertise and equipment. To do qPCR, you need primers that can locate the gene of the receptor you are interested in in the genome. This is a very daunting task for a little primer! Recently, we have run into difficulties with our primers for dopamine 1 and dopamine 2 receptors. We have ordered new primers, and our next task is to determine which primers are the most effective at targeting this gene. We have also run into some problems with our cryostat, which is used to slice tissue. Fortunately, our department has a state-of-the-art cryostat, and we have learned how to use it, and it works spectacularly! Clearly, this is another reality of research: you win some, you lose some. The important thing is to remember is that you have a goal, and that small hiccups shouldn’t dissuade you from research and making discoveries. To quote the tagline of one of the best science fiction shows of the 1990s, “The truth is out there!”

I think the most important thing for people to realize about the day-to-day lives of scientists is that we aren’t discovering gravity or the cure to polio every day. Some days are a wash, literally—regularly deep cleaning our bird room is one of the great joys of research. But some days are great, like when you finally manage to perfect that technique that you have been struggling with for weeks. I feel like an expert with the cryostat and subbed slides—there’s no better feeling than doing something easily after practicing for months. Slicing tissue is like riding a bike—you never forget. It’s important to learn as much as you can from people who know more than you, but it’s equally important to teach. I think a lot of people tend to think that scientists isolate themselves in their lab, barely ever emerging for food or sleep, laughing maniacally whenever their experiment works. Actually, that sounds pretty accurate, now that I have it all written out. But I guess scientists tend to not isolate themselves completely—we usually have a lab partner or a collaborator working with us. So it’s more like, you barely emerge from your lab for eating or sleeping, you laugh maniacally, and your lab partner is the last person you spoke face-to-face with in the past 3 days. Joy! (Of course, I’m being sarcastic. It’s been 5 days!). I have a new appreciation for the power of collaboration. And I think that is why the image of a scientist toiling alone in a lab bothers me so much—it ignores the fact that all scientists rely on others, and have others who rely on them. Perhaps if Frankenstein got his research peer-reviewed, his life would have gone very differently. As Newton said, “If I have seen further, it is by standing on the shoulders of giants.” Having stood on the shoulders of many giants myself, I look forward to the day that I can be a “giant” for another young scientist.


  1. Aragona, B. J., Liu, Y., Yu, Y. J., Curtis, J. T., Detwiler, J. M., Insel, T. R., & Wang, Z. (2006). Nucleus accumbens dopamine differentially mediates the formation and maintenance of monogamous pair bonds. Nature Neuroscience, 9(1), 133-139. DOI: 10.1038/nn1613.
Lauren Eisenman is a senior majoring in cellular/molecular neuroscience at Scripps College in Claremont, California. She is a 2017 Integrative Organismal Systems Physiology (IOSP) fellow working in Dr. Melissa Coleman’s lab at the W.M. Keck Science Department in Claremont, California. This summer, Lauren is funded by the APS and a grant from the National Science Foundation Integrative Organismal Systems (IOS) (Grant #IOS-1238831). In the future, Lauren plans to attend graduate school in a neuroscience program and pursue a career in academia.

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