Why New Music Feels Rewarding: The Nucleus Accumbens Study

Why does a song you have never heard before sometimes grab you within seconds, while another leaves you cold? A 2013 brain-imaging study from McGill University gave one of the clearest answers so far. The pleasure of new music is tied to a small reward hub deep in the brain, the nucleus accumbens, and to how strongly that hub "talks" with the auditory cortex, the part of the brain that stores what we have learned about sound over a lifetime.

In short: the more active the nucleus accumbens was while people heard an unfamiliar track, the more money they were willing to spend to own it. And the better the reward hub and the hearing regions worked together, the more valuable the music felt.

The short answer: reward meets memory

The study, led by neuroscientist Valorie Salimpoor in the lab of Robert Zatorre at the Montreal Neurological Institute, was published in Science in April 2013 under the title "Interactions Between the Nucleus Accumbens and Auditory Cortices Predict Music Reward Value."

Two findings stand out:

• The nucleus accumbens predicts liking. Its activity while a song played was the best single predictor of whether a listener would later pay for that song, and how much.
• The auditory cortex shapes taste. The reward hub did not work alone. The more rewarding a track was, the stronger the communication between the nucleus accumbens and regions of the auditory cortex (shown in yellow in the illustration above), which hold the sound patterns we have absorbed over years of listening.

Put simply, the brain seems to compare each new piece of music with an internal library of everything it has heard before, and the reward system responds to how that comparison plays out.

How the McGill experiment worked

Measuring "how much someone likes a song" is harder than it sounds. People are polite, inconsistent and easily swayed when they fill in rating scales. The McGill team solved this with real money.

According to the original reporting, 19 volunteers lay in a functional MRI scanner, which tracks changes in blood flow as a stand-in for brain activity. They listened to 60 short excerpts of music they had never heard. To make sure the tracks were neither random nor obviously familiar, the researchers chose them with music recommendation tools such as Pandora and Last.fm, matched to each person's stated tastes.

After each clip, the volunteers took part in an auction modelled on the iTunes store. They could bid nothing, or pay $0.99, $1.29 or $2 of their own money, and a higher bid made it more likely they would actually take the track home. That small financial sacrifice gave the scientists an honest, behaviour-based measure of how much each person valued each song.

When the brain scans were lined up against the bids, the pattern was clear. Songs that people went on to buy, and especially those they bid the most for, had produced the strongest response in the nucleus accumbens while they were playing.

Why the nucleus accumbens matters

The nucleus accumbens sits near the base of the forebrain and is a core part of the brain's reward system. It receives signals from dopamine-producing neurons and becomes active when we anticipate or receive things we find rewarding, from food to social approval. It is also one of the regions drugs of abuse act on, which is why music is sometimes described as engaging "the same circuits" as other pleasures.

That comparison needs care. Music does not hit the brain like a drug. What the research shows is that an abstract pattern of sounds, which has no survival value of its own, can recruit the same machinery the brain uses to tell us something is worth seeking out again. An earlier study from the same McGill group, published in 2011, used PET scanning to show that dopamine is released both while people wait for a favourite musical moment and when the "chills" actually arrive.

The 2013 study pushed this further. It looked at new music, where there are no memories of earlier pleasure to rely on, and still found the reward hub predicting value within a single listen.

Expectation: the secret ingredient

So what is the nucleus accumbens reacting to when you hear a track for the first time? The researchers' answer is expectation. As music unfolds, the brain constantly predicts what comes next: the next chord, the next beat, the return of a chorus. When a song confirms those predictions in a satisfying way, or breaks them in a clever one, the reward system responds.

Salimpoor summed it up in McGill's announcement: "What makes music so emotionally powerful is the creation of expectations."

Those predictions are built from experience. The auditory cortex stores statistical knowledge about the music you grew up with and keep listening to: the scales, rhythms and song structures that feel "normal" to you. Earlier research had already linked parts of this cortex to value-based judgements. The new study showed that its conversation with the reward hub tracks how much a new piece is worth to the listener.

This works much like a personal recommendation engine. Streaming services guess what you will enjoy based on what you already play; your auditory cortex does something similar, using a lifetime of listening to decide whether an unfamiliar song "makes sense" in a pleasing way.

Why musical taste differs so much

Because those internal templates are learned, they differ from person to person and from culture to culture. Someone raised on Greek rebetiko, Korean pop, Indian classical ragas or heavy metal will carry a different set of expectations, and so will feel rewarded by different surprises.

That helps explain a puzzle. The love of music is close to universal, yet individual tastes diverge wildly. The study also found that, although each volunteer bought different tracks, the brain activity linked to purchasing looked similar from person to person. The machinery is shared; the content it has been trained on is personal.

It also suggests why taste can change. Repeated exposure to a style slowly reshapes the patterns stored in the auditory cortex, which is why a genre that once sounded like noise can, after a few months, start to feel exciting.

How old is our love of music? A correction

Music is ancient, but some popular claims about its age mix up two separate finds:

• The Divje Babe "flute" from Slovenia is a cave-bear thigh bone with holes in it, now dated to roughly 50,000 to 60,000 years ago and linked to Neanderthals. Many researchers, however, argue that the holes were made by the teeth of carnivores such as hyenas, so its status as an instrument is still disputed. An early radiocarbon date of about 43,000 years was later judged unreliable.
• The Geissenklösterle flutes from southern Germany, made from bird bone and mammoth ivory by early modern humans, are about 42,000 to 43,000 years old. These are widely regarded as the oldest known musical instruments that are clearly human-made.

Either way, people have been shaping sound for pleasure for tens of thousands of years, long before anyone could buy a song for $1.29.

What this means for everyday listening

A few practical takeaways follow from the research:

• Give new music more than one chance. If your brain's templates don't yet fit a genre, early listens may feel flat. Familiarity builds the expectations that make later listens rewarding.
• Recommendation tools work because the brain works that way. Suggestions "similar to what you like" lean on the same pattern-matching your auditory cortex already does.
• Surprise matters as much as comfort. Pieces that play with expectation, with a delayed resolution or an unexpected key change, are often the ones that give chills.
• One study is not the last word. fMRI measures blood flow, not thoughts, and 19 people is a modest sample. Later work has broadly supported the role of the reward system in musical pleasure, but the details are still being studied.

For the curious, the illustration at the top of this page, adapted from the McGill research, shows the nucleus accumbens in dark blue and the auditory regions in yellow: two very different parts of the brain that, together, decide whether a new song is one you will want to hear again.

Sources: Salimpoor V.N. et al., Science 340 (2013): 216; ScienceDaily / McGill University (April 2013); McGill University news release; Smithsonian Magazine; Wikipedia: Divje Babe flute; Wikipedia: Geissenklösterle.

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