One day several years ago Valorie Salimpoor took a drive that would change the course of her life. She was at the peak of what she now calls her “quarter-life crisis,” not knowing what kind of career she wanted or how she might use her undergraduate neuroscience training. Hoping an outing might clear her head, that day she jumped in her car and switched on the radio. She heard the charging tempo and jaunty, teasing violin of Johannes Brahms’s Hungarian Dance No. 5.
“This piece of music came on, and something just happened,” Salimpoor recalls. “I just felt this rush of emotion come through me. It was so intense.” She pulled over to the side of the street so she could concentrate on the song and the pleasure it gave her.
When the song was over, Salimpoor’s mind raced with questions. “I was thinking, wow, what just happened? A few minutes ago I was so depressed, and now I’m euphoric,” she says. “I decided that I had to figure out how this happened — that that’s what I’m going to do with the rest of my life.”
Music moves people of all cultures, in a way that doesn’t seem to happen with other animals. Nobody really understands why listening to music — which, unlike sex or food, has no intrinsic value — can trigger such profoundly rewarding experiences. Salimpoor and other neuroscientists are trying to figure it out with the help of brain scanners.
Researchers from Stanford reported that when listening to a new piece of classical music, different people show the same patterns of synchronized activity in several brain areas, suggesting some level of universal experience. But obviously no one’s experience is exactly the same. Salimpoor’s group reported that when you listen to a song for the first time, the strength of certain neural connections can predict how much you like the music, and that these preferences are guided by what you’ve heard and enjoyed in the past.
After Salimpoor had the car epiphany, she rushed home to her computer and Googled “music and the brain.” That led her to graduate school at McGill University, working in the lab of neuroscientist Robert Zatorre.
A few years ago, Salimpoor and Zatorre performed another type of brain scanning experiment in which participants listened to music that gave them goosebumps or chills. The researchers then injected them with a radioactive tracer that binds to the receptors of dopamine, a chemical that’s involved in motivation and reward. With this technique, called positron emission tomography or PET, the researchers showed that 15 minutes after participants listened to their favorite song, their brains flooded with dopamine.
The dopamine system is old, evolutionarily speaking, and is active in many animals during sex and eating. “But animals don’t get intense pleasures to music,” Salimpoor says. “So we knew there had to be a lot more to it.”
In a newer experiment, the researchers used functional magnetic resonance imaging (fMRI) to track real-time brain activity as participants listened to the first 30 seconds of 60 unfamiliar songs. To quantify how much they liked the music, participants were given the chance to buy the full version of each song — with their own money — using a computer program resembling iTunes. The program was set up like an auction, so participants would choose how much they were willing to spend, with bids ranging from $0 to $2.
The brain scans highlighted the nucleus accumbens, often referred to as the brain’s ‘pleasure center’, a deep region of the brain that connects to dopamine neurons and is activated during eating, gambling and sex. It turns out that connections between the nucleus accumbens and several other brain areas could predict how much a participant was willing to spend on a given song. Those areas included the amygdala, which is involved in processing emotion, the hippocampus, which is important for learning and memory, and the ventromedial prefrontal cortex, which is involved in decision-making.
So why is it that one person might spend $2 on a song while another pans it? Salimpoor says it all depends on past musical experiences. “Depending on what styles you’re used to — Eastern, Western, jazz, heavy metal, pop — all of these have very different rules they follow, and they’re all implicitly recorded in your brain,” she says. “Whether you realize it or not, every time you’re listening to music, you’re constantly activating these templates that you have.”
Using those musical memory templates, the nucleus accumbens then acts as a prediction machine, she says. It predicts the reward that you’ll feel from a given piece of music based on similar types of music you’ve heard before. If you like it better than predicted, it registers as intense pleasure. If you feel worse than predicted, you feel bored or disappointed.
But for now the study has given Salimpoor a new way to think about what happened to her that day in the car. Music, she says, is an intellectual reward. “It’s really an exercise for your whole brain.”