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New study suggests music can be addictive in humans
Throughout recorded history in every culture around the globe, music has existed in one form or another. Listening to favorite music is universally accepted as a pleasurable and often relaxing experience. For years, scientists have pondered why music plays such a large and important role in life. But recently, a group of neuroscientists, led by Canadian researcher Valorie Salimpoor, discovered that music elicits the same reaction in the brain as would the use of cocaine or the downing of a delicious meal.
A group of scientists from The Montreal Neurological Institute and Hospital at McGill University discovered listening to pleasurable music causes the brain to release dopamine, a neurotransmitter in the brain that reinforces gratifying behavior. The group found that dopamine is released when those listening to music reached peak emotional arousal, a finding the team expected. However, the group also discovered the anticipation of hearing pleasurable music can induce a dopamine release, a result Salimpoor and her team consider the most important finding.
“What’s really astonishing is we found dopamine released before the peak emotional arousal, in anticipation of it,” Salimpoor said. “I think that is one of the more interesting findings of the paper because it suggests why and how we like music.”
Dr. Colum MacKinnon, an assistant professor in the Department of Physical Therapy and Human Movement Sciences at Northwestern University’s Feinberg School of Medicine, agreed the anticipatory reaction was the most significant finding in the study.
“For me, this is the beauty of the study,” MacKinnon said. “Basically they looked at what parts of the brain are involved in the anticipatory response and what are the regions involved in the actual response itself when the feeling of pleasure comes.”
Although many people think of dopamine as a “feel-good” chemical, according to Salimpoor, it is actually not the main “feel-good” chemical in the brain. However, it does play an important role in causing addiction. Dopamine affects the brain’s motivation center, thus it is responsible for sustaining behavior.
“This is important because it is providing concrete neurochemical evidence for why we continue to listen to music,” Salimpoor said. “The reason why the dopaminergic system is relevant is because this system in the brain is actually a phylogenetically ancient system. It has evolved to reinforce highly adaptive behaviors such as eating and sex, for example, to sustain our species. So when dopamine is released, these behaviors are strongly reinforced. It’s the brain’s way of ‘stamping in’ that behavior so it is repeated.”
To conduct the study, Salimpoor and her team asked participants to choose instrumental music they considered intensely pleasurable but to which they had no specific memory attached. Salimpoor said it was important to use instrumental music to ensure reactions were not linked to language. To obtain the most objective results, it was also important for participants to choose music they didn’t knowingly have any attachment to.
As participants listened to their selected music, the team used equipment similar to that used in lie detection to measure physiological changes, such as an increase in heart rate, respiration, blood volume pulse and temperature. Additionally, the team monitored the participants’ electrodermal response, which, once known as the galvanic skin response, is the measure of sweat on a person’s fingers. Salimpoor said measuring electrodermal skin response is one of the best, most sensitive measures used to see whether people are emotionally aroused. These physiological changes were representative of “chills” or “musical frisson,” a well-established marker of peak emotional response. This is a reaction in which music can actually cause the experience of chills.
The team began by using positron emission tomography, or PET, to determine how much dopamine was released and where in the brain the release occurred. The team then used functional magnetic resonance imaging, or fMRI, to determine when the dopamine release took place.
“You get this fairly prolonged increase in activity,” MacKinnon said. “We look for blood flow changes, and that’s what the fMRI measures. The PET study is looking for changes in binding potential of dopamine. It’s an indirect measure of basically the receptor activity in the nucleus.”
The team determined that during peak emotional response to music, dopamine was released in the nucleus accumbens, the same region where dopamine is released when people are experiencing a cocaine rush. However, the dopamine released in anticipation of this peak emotional response was in a different area of the brain called the caudate nucleus.
“The reason why this is significant is because this particular region has very tight connections with the prefrontal cortex of the brain,” Salimpoor said. “This part of the brain is sort of uniquely developed in humans, meaning the elaborate development of this region is what separates us from other animals because it houses complex thinking. This might begin to explain why we appreciate aesthetic stimuli.”
The results of Salimpoor and her colleagues are also of great interest to other neuroscientists studying the effects of music on the human brain and behavior. Dr. Hauke Egermann, an expert in systematic musicology and media sciences at McGill’s Schulich School of Music, is working on a project continuously measuring music listeners’ psychological and physiological emotional response in live concert settings. His team’s experiment focuses on violations and confirmations of musical expectations.
“The neuroimaging results presented in [Salimpoor’s] paper highlight the importance of this mechanism and its neurophysiological underpinnings,” Egermann said. “Furthermore, they prove again music’s capability to induce synchronized, real-life emotions, similar to those associated with other kinds of stimulations.”
Now that researchers have determined where and when dopamine is released in the brain in response to pleasurable music, their next step is to determine how memory plays a role in this response. The team will use entirely new music this project’s participants have never heard in an attempt to see if initial results can replicated. How these responses happen within the brain will also be examined to determine how it is possible for a sequence of tones to become pleasurable.
Conducting this study helped Salimpoor and her team understand how simple sounds can become pleasurable for humans and possibly even other high-order primates. It reaffirms the complexity of the human brain and shows that humans experience pleasure based on how they interpret the music, not from the music itself.
“These experiments don’t answer the question of how music originated in the first place, but help us understand why music has been around for so long—because it works on the brain’s most powerful reinforcement and addiction circuit,” Salimpoor said. “Perhaps our society is mildly addicted to music, which can explain why we all have iPods and are willing to spend so much money achieving music-related experiences, like better speakers or live concert tickets.”
To see a list of the chill-inducing music please go to http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0007487#s5
Sound samples of chill-inducing music is available at Zlab.mcgill.ca/emotion/