Music: brain

Science World, Feb 7, 2003

Wonder why you can tell when a singer is off-key? Researchers at Dartmouth College in Hanover, N.H., have found one brain area responsible: rostromedial prefrontal cortex, located just behind the forehead.

"People have long suspected the brain maintains a map of musical keys," says neuroscientist Petr Janata. He explains that everything in nature--whether a snowflake or music--has an underlying shape. And the structure of Western music, with its 24 major and minor keys, can be mapped in a mathematical model in the shape of a donut, or torus. Keys with similar notes and chords are spaced closer together on the donut.

"You can't see it, but music moves around this geometric space," says Janata. "And our brain learns to perceive how music should move within this space, and how different keys and patterns relate to each other [and to detect a sour note!], simply through a lifetime of passive listening." But since this musical shape mirrors a psychological space, "I wanted to know where the brain does it."

Using functional magnetic resonance imaging (body-function scanning technology), Janata's team followed the brain activity of eight people as they listened to a piece of music specially composed to move through all 24 keys. Subjects were instructed to pick out specific notes and instrument sounds, which were strategically hidden in the music to track key changes. Researchers also followed the music's key changes with a computerized model of the torus. Their result: While many parts of the brain responded to the music, the rostromedial prefrontal cortex was the only part to accurately keep up with the musical donut. Besides processing music, scientists have found this brain region is also involved in processing emotion. "This might explain why music makes you feel like dancing," adds Janata.