Unexpected but consonant notes in music activate the reward centers in our brains, new research reveals.

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Doesn’t that unexpected, but perfect, note peppered into a song send shivers down your spine? You’re not alone. New research at the McGill University shows that a dash of the unexpected in music lights up our brain’s reward centers, and helps us learn about music as we listen.

Unexpected by not unpleasant

The team, led by PhD candidate Ben Gold, worked with 20 volunteers through a musical reward learning task. The task consisted of a game where participants had to pick a color and then a direction. Each choice had a certain probability of returning a consonant (pleasurable) musical excerpt or a dissonant (unpleasurable) one.

Over time, participants started to learn which choices were more likely to produce either of these excerpts, which was what the team wanted. The test was designed to create an expectation in the mind of participants — either for musical dissatisfaction or enjoyment. Each participant had their brain activity measured using functional magnetic resonance imaging (fMRI) during the trial.

Pooling all this data together, the team determined reward prediction error for each choice the participants made. This error is the difference between expected reward and the actual outcome of their choice. Comparing these errors to MRI data revealed that reward prediction errors correlated with activity in the nucleus accumbens (NA), a brain region previously studies linked to feelings of musical pleasure. This is the first evidence that musically-elicited reward prediction errors cause musical pleasure, the team writes, as well as the first time an aesthetic reward such as music has been shown to create this kind of response. Previous studies have found similar results, but they worked with more tangible rewards such as food or money.

Finally, the team explains that subjects whose reward prediction errors most closely mirrored activity in the NA learned which choices lead to consonant tones faster than their peers. This, the team writes, establishes music as a neurobiological reward capable of motivating learning. The pleasurable feeling elicited by this effect motivates us to listen again and again, they explain, which helps us learn.

“This study adds to our understanding of how abstract stimuli like music activate the pleasure centres of our brains,” says Gold. “Our results demonstrate that musical events can elicit formally-modeled reward prediction errors like those observed for concrete rewards such as food or money, and that these signals support learning. This implies that predictive processing might play a much wider role in reward and pleasure than previously realized.”

The paper ” Musical reward prediction errors engage the nucleus accumbens and motivate learning” has been published in the journal Proceedings of the National Academy of Sciences.