Music and pleasure
Music is strongly associated with the brain's reward system. It's the part of the brain that tells us if things are valuable, or important or relevant to survival, said Robert Zatorre, professor of neurology and neurosurgery at Montreal Neurological Institute.
One brain structure in particular, called the striatum, releases a chemical called dopamine in response to pleasure-related stimuli. Imaging of the brain can reveal this process is similar to what happens in your brain in response to food or sex.
But unlike those activities, music doesn't have a direct biological survival value. "It's not obvious that it should engage that same system," Zatorre said.
Musicians can't see inside their own brains, but they're aware of moments of tension and release in pieces, and that's what arrangers of music do.
Zatorre and colleagues did an experiment where they used whatever music participants said gave them pleasure to examine this dopamine release. They excluded music with words in order to focus on the music itself rather than lyrics -- the melodic structure, for example.
At the point in a piece of music when people experience peak pleasure, part of the brain called the ventral striatum releases dopamine. But here's something even more interesting: Dopamine is released from a different brain area (the dorsal striatum) about 10 to 15 seconds before the moment of peak pleasure.
Why would we have this reaction before the most pleasurable part of the piece of music? The brain likes to investigate its environment and figure out what's coming next, Zatorre explains.
"As you're anticipating a moment of pleasure, you're making predictions about what you're hearing and what you're about to hear," he said. "Part of the pleasure we derive from it is being able to make predictions."
So if you're getting such a strong dopamine rush from music -- it could even be comparable to methamphetamines, Zatorre said -- why not make drug addicts listen to music? It's not quite that simple.
Neuroscientists believe there's basically one pleasure mechanism, and music is one route into it. Drugs are another. But different stimuli have different properties. And it's no easier to tell someone to replace drugs with music than to suggest eating instead of having sex -- these are all pleasurable activities with important differences.
Rocking to the beat
Did you know that monkeys can't tap their feet to songs, or recognize beats?
It appears that humans are the only primates who move to the beat of music. Aniruddh Patel at the Neurosciences Institute in San Diego, California, speculates that this is because our brains are organized in a different way than our close species relatives. Grooving to a beat may be related to the fact that no other primates can mimic complex sounds.
Curiously, some birds can mimic what they hear and move to beats. Patel's research with a cockatoo suggests the beat responses may have originated as a byproduct of vocal mimicry, but also play a role in social bonding, Patel said. Armies train by marching to a beat, for instance. Group dancing is a social activity. There also are studies showing that when people move together to a beat, they're more likely to cooperate with each other in nonmusical tasks than if they're not in synch.
"Some people have theorized that that was the original function of this behavior in evolution: It was a way of bonding people emotionally together in groups, through shared movement and shared experience," Patel said.
Another exciting arena of research: Music with a beat seems to help people with motor disorders such as Parkinson's disease walk better than in the absence of music -- patients actually synchronize their movements to a beat, Patel said.
"That's a very powerful circuit in the brain," he said. "It can actually help people that have these serious neurological diseases."
There's also some evidence to suggest that music can help Alzheimer's patients remember things better, and that learning new skills such as musical instruments might even stave off dementia.
There still needs to be more research in these areas to confirm, but Limb is hopeful about the prospect of musical engagement as a way to prevent, or at least delay, dementia.