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Your Brain on Music By Linda Nevin In the past few years, imaging studies of living human brains have shown that the minds of accomplished musicians are different from those of non-musicians, both in anatomy and in patterns of neural activation when listening to music1-4. Neuroscientists speculate that the distinct activity seen in the minds of musicians represents the “musician’s ear” – the learned ability to hear more in a musical piece, such as harmonies, key changes or variations in timing. However, the signatures of a musician’s brain might just as well reflect his innate talent. In a recent study, Dr. Elizabeth Margulis of the University of Arkansas and her collaborators cleverly distinguished the roles of nature and nurture in the building of a musician’s brain. The researchers identified a complex network of regions that buzz wildly in the brains of accomplished musicians when they hear familiar music5. Their results strongly suggest that the development of this specialized network is the result of years of training. Most functional imaging studies of music-listening have compared the brains of non-musicians with those of accomplished musicians, who likely also share an innate sensitivity to the details of a song. In these studies, any distinctions found between the musicians and non-musicians could be the result of either aptitude or training. Instead, Margulis and colleagues compared two groups of highly accomplished musicians—violinists and flutists—who likely have similar musical aptitude, but different “musician’s ears,” specialized in listening to their instrument. The researchers selected excerpts from two similar J.S. Bach Partitas, one for the violin and one for the flute, to play for their musician subjects as an MRI scanner recorded activity throughout their brains. All subjects listened to each song in turn, and the spatial patterns of neural activity were compared between musicians listening to their own instrument (e.g., flutists listening to the flute Partita) and musicians listening to the other instrument (e.g., violinists listening to the flute Partita). Margulis and colleagues found that a network of left brain areas associated with language processing and body movements is most strongly activated when a musician listens to her own instrument. Because the musically gifted are unlikely to be hard-wired to choose the flute or the violin, the heightened activation of this network is more likely the result of training than talent. The association of language processing and motor systems with knowledgeable music-listening is no surprise to neural musicologists. Our musical ability is closely married to our use of language; processing of language and music are localized to a common set of areas in the brain. For example, a dissonant note in a musical progression and a semantically incorrect word at the end of a sentence (e.g., “He spread his warm bread with socks”) both activate a neural response like an alarm bell in Broca’s area, a small region on the wrinkled surface of the brain just beneath the hairline at eyebrow-level6-8. This alarm bell has been posited to underlie the double-take response that makes us evaluate a phrase more carefully when it doesn’t match our expectations. Broca’s area, along with two other language processing-associated regions is a part of Margulis et al’s network that shows increased activation when a musician hears his own instrument playing Bach. We can imagine that the activation in Broca’s area represents a chorus of alarm bells ringing when the performance did not perfectly match the subjects’ expectations. Because all the musician subjects had played the songs before, they likely had an internal score to compare with what they heard. The association of music-listening with brain regions used to control body movement also has precedent. Primates, including humans, have a population of “mirror” brain cells in that are active when we move a muscle, and when we passively watch someone else move in the same way. These cells are believed to underlie our ability to understand the actions of others. In the case of these musicians, hearing their own instrument played activated brain areas that plan and initiate movement, as if the subjects imagined playing the piece themselves. A similar response has recently been observed in non-human musicians, too; researchers at Duke University recently reported that songbirds have mirror neurons that fire when a bird sings, or hears another bird sing a similar song9. From an evolutionary perspective, perhaps both the avian and human musicians flex their own motor systems in response to a matched “mating call” in order to practice and compare, increasing fitness by becoming ever better performers. References: 2. Gaab, N.; Schlaug, G., Musicians differ from nonmusicians in brain activation despite performance matching. Ann N Y Acad Sci 2003, 999, 385-8. 3. Gaser, C.; Schlaug, G., Gray matter differences between musicians and nonmusicians. Ann N Y Acad Sci 2003, 999, 514-7. 4. Hyde, K. L.; Lerch, J. P.; Zatorre, R. J.; Griffiths, T. D.; Evans, A. C.; Peretz, I., Cortical thickness in congenital amusia: when less is better than more. J Neurosci 2007, 27, (47), 13028-32. 5. Margulis, E. H.; Mlsna, L. M.; Uppunda, A. K.; Parrish, T. B.; Wong, P. C., Selective neurophysiologic responses to music in instrumentalists with different listening biographies. Hum Brain Mapp 2007. 6. Hagoort, P.; van Berkum, J., Beyond the sentence given. Philos Trans R Soc Lond B Biol Sci 2007, 362, (1481), 801-11. 7. Kutas, M.; Hillyard, S. A., Reading senseless sentences: brain potentials reflect semantic incongruity. Science 1980, 207, (4427), 203-5. 8. Maess, B.; Koelsch, S.; Gunter, T. C.; Friederici, A. D., Musical syntax is processed in Broca’s area: an MEG study. Nat Neurosci 2001, 4, (5), 540-5. 9. Prather, J. F.; Peters, S.; Nowicki, S.; Mooney, R., Precise auditory-vocal mirroring in neurons for learned vocal communication. Nature 2008, 451, (7176), 305-10.
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