Sex, drugs, and rock & roll chemistry in the brain
The same brain-chemical system that mediates feelings of pleasure from sex, recreational drugs, and food is also critical to experiencing musical pleasure, according to a study by 不良研究所 researchers published today in the Nature journal Scientific Reports.
鈥淭his is the first demonstration that the brain's own opioids are directly involved in musical pleasure,鈥� says cognitive psychologist Daniel Levitin, senior author of the paper. While previous work by Levitin鈥檚 lab and others had used neuroimaging to map areas of the brain that are active during moments of musical pleasure, scientists were able only to infer the involvement of the opioid system.
In the new study, Levitin鈥檚 team at 不良研究所 selectively and temporarily blocked opioids in the brain using naltrexone, a widely prescribed drug for treating addiction disorders. The researchers then measured participants鈥� responses to music, and found that even the participants鈥� favorite songs no longer elicited feelings of pleasure.
鈥淭he findings, themselves, were what we hypothesized,鈥� Levitin says. 鈥淏ut the anecdotes -- the impressions our participants shared with us after the experiment -- were fascinating. One said: 鈥業 know this is my favorite song but it doesn't feel like it usually does.鈥� Another: 鈥業t sounds pretty, but it's not doing anything for me.鈥欌��
Things that people enjoy 鈥� alcohol, sex, a friendly game of poker, to name a few 鈥� can also lead to addictive behaviors that can harm lives and relationships. So understanding the neurochemical roots of pleasure has been an important part of neuroscience research for decades. But scientists only recently developed the tools and methods to do such research in humans.
Still, this study proved to be 鈥渢he most involved, difficult and Sisyphean task our lab has undertaken in 20 years of research,鈥� Levitin says. 鈥淎nytime you give prescription drugs to college students who don鈥檛 need them for health reasons, you have to be very careful to ensure against any possible ill effects.鈥� For example, all 17 participants were required to have had a blood test within the year preceding the experiment, to ensure they didn鈥檛 have any conditions that would be made worse by the drug.
Music鈥檚 universality and its ability to deeply affect emotions suggest an evolutionary origin, and the new findings 鈥渁dd to the growing body of evidence for the evolutionary biological substrates of music,鈥� the researchers write.
This work was supported by funding from the Natural Sciences and Engineering Research Council of Canada.
鈥淎nhedonia to music and mu-opioids: Evidence from the administration of naltrexone,鈥� Adiel Mallik, Mona Lisa Chanda & Daniel J. Levitin. Scientific Reports, published online Feb. 8, 2017.聽DOI: 10.1038/srep41952
PHOTO: Daniel Levitin 聽CREDIT: J. Mogil/不良研究所