Mittwoch, Januar 08, 2003

 

In the key of life
Music 'grabs hold of our brains and generates an emotional response'

Margaret Munro
National Post

"Music is basically a legal drug," says neuroscientist Petr Janata, who has just published a study that helps explain why it is so hard to forget some tunes.

Researchers have known for years that music can bring tears to the eyes, whip teenagers into a near-euphoric state and get consumers into a giving -- and buying -- mood. Now, Janata's team at Dartmouth College is a step closer to explaining how it stimulates the brain.

In a report in the journal Science today, the neuroscientists show how the region in the brain that tracks music is also active during reasoning and memory retrieval. The region, called the rostromedial prefrontal cortex, is right behind the forehead. It is also associated with processing emotions and maintaining a sense of self.

"This all helps explain how music is tied in to our personal experience," Janata says, referring to the way a song can bring back memories of childhood road trips or the sensations of a first slow dance.

It also points to a possible explanation of why you might suddenly find yourself obsessively humming a particularly annoying Barney ditty: "when all of a sudden you have a tune running through your head, or worse still, you can't get it out," Janata says. The rostromedial area is associated with spontaneous thought and a similar spontaneous process may be at work on the musical front.

While finding the brain's musical tracking centre is intriguing, Janata stresses it is just one piece of the musical puzzle.

Music is not necessary for human survival, but people throughout history have created music and integrated it into cultural and religious ceremonies. The modern manifestation is a multi-billion-dollar industry.

"Music is something our brain wants to hear," Janata says. "Something inside us craves it."

Most people's brains quickly tire of tunes that are too predictable, such as advertising jingles. But most brains "don't tend to like" music that is too difficult to understand, such as free-form jazz.

The most enduring and popular music has an intermediate level of complexity that makes it "interesting" to the brain.

"It sort of grabs hold of our brains and generates an emotional response," Janata says.

Exactly how it does this remains largely a mystery. But by watching -- literally -- how music plays in the brain, scientists are gaining insight into how music stimulates the grey matter, and also into basic brain function.

Western "tonal" music -- which includes everything from rock to jazz to classical music -- has a structure that lends itself to studying how the brain processes "expectancy," Janata says.

"Our main task as organisms trying to survive in the world is to interact appropriately with the environment," he says. Our brains must understand the environment and put it in proper context, so we know what to expect around the next corner on the highway or when we get out of bed in the morning.

Similar "expectancy" processing is believed to apply to music, and the way we expect it to follow basic harmonic rules.

"It is the fulfillment and violation of these expectations which generates the emotional response that we have to pieces of music." Janata says.

This could also help explain why music from unfamiliar cultures --or the latest creation from teen subcultures -- can seem very strange, Janata says. But the nuances and subtleties of the music come through when one listens to the music long enough.

Most people have been exposed to so much Western music, be it through television, radio or formal musical training, that they have an internalized sense of "harmonic" space.

For example, "we have an explicit memory for the sequence and the pitches that make up Jingle Bells," Janata says, and our brains are quick to note when a sour key violates that expectation.

To explore how the brain maintains musical "context," Janata and his colleagues asked eight people, who had some degree of musical experience, to listen to an eight-minute melody composed by a student in the lab. The tune moves through all 24 major and minor keys and was crafted to shift in particular ways between and around the different keys.

The researchers scanned the volunteers' brains using functional magnetic resonance imaging (MRI) as they listened to the melody and looked for brain activity triggered by the music as it moved through the keys. They soon honed in on the rostromedial area at the front of the brain.

"It seemed to be tracking the melody as it moved through the different keys," Janata says.

He also says the rostromedial -- and its tracking capacity -- help explain how we can recognize songs when they are played in different keys. And why it hurts the ears when a pianist hits a wrong note even when playing a piece we have never heard before, or when someone sings off key.

mmunro@nationalpost.com

posted by nadia 7:05 AM