We all know that certain pieces of music can evoke strong emotional responses in people. Now, a research team from Canada's McGill University has uncovered evidence that reveals exactly what causes such feelings of euphoria and ecstasy and why music is so important in human society. Using a combination of brain scanning technologies, the study has shown that the same neurotransmitter which is associated with feeling pleasure from sex and food is released in the brain when listening to good music.

That humans can derive intense pleasure from such things as food, drugs, money and sex is well known. All of these feelings of reward generally involve the activity of a certain neurotransmitter in the brain – dopamine. It's a mechanism that's necessary for survival, caused by psychoactive drugs or by tangible items which offer secondary rewards of some kind.

Abstract external stimuli, like music or art, can often trigger heightened pleasure responses in people, even though they can't be thought of as vital for survival or the result of conditioned reinforcement. They are perceived as being rewarding rather than actually having a direct or chemical influence.

Music's effect on our emotional state is, of course, also well-known – as witnessed by the increase in our population as result of recordings by Barry White or Etta James, or the floods of tears accompanying a moving piece from Bach or Beethoven. Previous neuroimaging studies have hinted that the emotion and reward circuits in the brain have a lot to do with the sensations experienced when listening to good music.

Researchers Valorie N. Salimpoor, Mitchel Benovoy, Kevin Larcher, Alain Dagher and Dr. Robert Zatorre from the Montreal Neurological Institute and Hospital at McGill University and the Centre for Interdisciplinary Research in Music, Media, and Technology have now provided direct evidence.

Even though we know what pleasure is, it's a phenomenon that's difficult to assess objectively. However, highly pleasurable experiences often result in noticeable physiological symptoms like changes in electrodermal activity, heart rate, respiration and so on – this "chills" response can therefore be measured. This measurement can be used to determine the exact moment of heightened pleasure, to help pinpoint what's going on in the brain when the chills response kicks in.

As musical tastes vary considerably, participants in the study were asked to choose their own pieces of highly pleasurable music. Volunteers were also asked to identify a piece of neutral music for control purposes, that was not unpleasant but didn't elicit any sort of heightened emotional response. Music used in the study included classical works by Beethoven, Chopin and Tchaikovsky, film scores from A Clockwork Orange and Kill Bill, Flamenco guitar by Rodrigo Y Gabriela and rock from Led Zeppelin, as well as jazz, blues, techno and folk.

Each volunteer went through two testing sessions, one with the neutral music and one with the pleasure music of choice. Positron Emission Tomography (PET) brain imaging revealed increased endogenous dopamine transmission during the pleasure session compared to the neutral session, confirming the association between musical enjoyment and dopamine release in the mesolimbic and mesostriatal reward systems. The research team also wanted to discover whether the release of dopamine was associated with the actual reward of listening to music or from the anticipation of what's to come.

PET does not give the kind of temporal resolution necessary for the examination of this kind of distinction, so the team also sought the help of a Functional Magnetic Resonance Imaging (fMRI) machine. During the fMRI stage of the testing, volunteers were asked to indicate when they experienced peak emotional responses to the same pieces of music. This information was then used to identify anticipations and peak experience time points.

The results showed that the release of dopamine was not constant throughout the whole piece but restricted to moments prior to and during peak moments. Activity was found to fire in the caudate region of the brain when the listener anticipated the emotional high, whereas during the experience itself, dopamine release was concentrated in the striatum system.

"Music is unique in the sense that we can measure all reward phases in real-time, as it progresses from baseline neutral to anticipation to peak pleasure all during scanning," says lead investigator Salimpoor. "It is generally a great challenge to examine dopamine activity during both the anticipation and the consumption phase of a reward. Both phases are captured together online by the PET scanner, which, combined with the temporal specificity of fMRI provides us with a unique assessment of the distinct contributions of each brain region at different time points."

The experiments are said to "provide the first direct evidence that the intense pleasure experienced to music is associated with dopamine activity in the mesolimbic reward system, including both dorsal and ventral striatum." They further show that the anticipation of sonic pleasure also results in reward systems being activated, and that the activity is concentrated in a different area of the brain than the actual experience.

The paper, entitled Anatomically distinct dopamine release during anticipation and experience of peak emotion to music, has been published in the journal Nature Neuroscience.

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