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More than a stuffy gramarian: Broca's area also helps us appreciate a nice tune.
Published online 23 April 2001 | Nature | doi:10.1038/news010426-4
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Chords strike a grammatical note
The brain region that senses sentences also tells music from noise.
More than a stuffy gramarian: Broca's area also helps us appreciate a nice tune.
The region of the brain that allows us understand whether a sentence makes sense may also help us tell the difference between a symphony and cacophony new research suggests.1
The Broca's area -- a brain region that processes the syntax, or word arrangement in a sentence -- is activated when people hear a musical chord in the wrong place in a traditional progression of chords. So Burkhard Maess and colleagues at the Max Planck Institute of Cognitive Neuroscience in Leipzig, Germany find.
This suggests that our brains recognise the constituents of musical and linguistic sequences in the same way. "It looks like tonal syntax is closely analogous to the part of language we call grammar," says Carol Krumhansl, a psychologist at Cornell University in New York who studies music perception.
Maess's team used a technique called magnetoencephalography (MEG) to monitor nerve impulse changes in the brains of subjects listening to sequences of five musical chords.
"Click here to hear the sequences":images/stim1.wav
Brain activity remained constant when the chord sequence followed the rules of western classical music: a progression of five, 'in-key' chords. But when the sequence included a miss-fit chord at the end, activity in the Broca's area increased -- just as it would if a listener detected a word out of place at the end of a sentence.
The effect was weaker or absent when the wrong chord was third in the sequence. This, Maess argues, is because the subjects had not heard enough chords by that point to predict how the sequence should be progressing, and therefore tell whether it was wrong or not.
To ensure that they were measuring the musical equivalent of verbal syntax the researchers chose a special type of chord -- a 'Neapolitan sixth' -- as the odd chord. This chord is in the same major key as the others and follows the rules of music theory in terms of its tone. "The chord would be accepted in a different position," says Maess. Putting the chord in the sequence was like putting a real word in the wrong place in a sentence.
The Broca's area had until now been implicated only in our understanding of language. Now, says Maess, "our idea of what the area is doing has been enlarged." His team's findings indicate that the Broca's area is involved in processing complex, rule-based information associated with sounds, more fundamental than the rules of music or language alone, he says.
The work is "very exciting," says Krumhansl because little is understood about why we possess an ability to appreciate music. Understanding how syntactic information is processed in the brain, "might provide some basic insight about why we have music," she argues.
Moreover, musical training is known to enhance verbal abilities; the research suggests that this may happen because training refines the same region of the brain. "Our aim is to understand how the brain works," says Maess, "but there is hope to develop techniques for treating patients who have language disabilities."
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