Wednesday, March 09, 2005

About that song that keeps repeating in your head...
Technology & Science
Cosmic Log
by Alan Boyle

Annoying songs take root in your auditory cortex

• March 9, 2005 | 7:20 p.m. ET
Where the earworms live: At one time or another, everyone's had a tune pop into their head and stay there, even though you wish it would just go away. Those meddlesome melodies are known as sticky songs, or "earworms," and over the past couple of years, hundreds of Cosmic Log readers have sent in contributions to the earworm list.

In Thursday's issue of the journal Nature, researchers report that they have discovered the place in the brain where earworms hide out. It should come as little surprise that the center for earworm activity is the auditory cortex, the same place where sounds are perceived.

Researchers from Dartmouth College and the University of Aberdeen worked with 15 experimental subjects to develop individualized playlists — including songs with lyrics, such as the Rolling Stones' "Satisfaction," as well as instrumental pieces such as the theme from "The Pink Panther." (Are those earworms working on you yet?)

Each listener tagged certain tunes as familiar, and others as unfamiliar. Then the tunes were played while the listener was lying in a magnetic resonance imaging scanner. At various points in the soundtrack, the music went silent for 3 to 5 seconds, and researchers watched how the brain responded.

During the gaps in the unfamiliar music, activity in the auditory cortex diminished. But when there was a gap in a familiar tune, the auditory cortex kept working away.

"It's like the brain is still hearing the music," one of the researchers, Dartmouth's David Kraemer, told me today. "It's still activating that part of the brain that’s activated when you’re hearing the music. ... And it's interesting to note that we didn’t instruct them to imagine the silent part. It's something that they just did spontaneously."

The researchers also saw a difference between the vocals and the instrumentals: Songs with lyrics activated an area known as the auditory association cortex, or Brodmann's area 22 — which links sounds with other aspects of experience, such as word recognition. The instrumental tunes sparked a more basic level of processing in the primary auditory cortex.

Kraemer speculated that when you hear a song with words, you use the words as a shorthand for the full melody — while a wordless melody forces your brain to go farther back to the notes themselves. "You react only as far back as you need to, to reconstruct the relevant part of the experience," he said.

Perhaps this explains why songs with lyrics tend to be "stickier" than instrumental tunes, and why it's so hard to stop an earworm in its tracks. Your auditory cortex wants to run through the entire experience of "Who Let the Dogs Out," even though the rest of your brain is longing to stop the music.

Earworms per se are not the focus of Kraemer's research interest. Rather, he and his colleagues are trying to understand the parallels between sensory perception and sensory memories. Kraemer said the research supports the view that mental imagery is "perception in reverse": that the process of remembering an experience retraces the neural route that was involved in perceiving that experience.

There's already evidence that visual imagery works that way — and now auditory imagery appears to follow a similar process.

Does knowing all this render you immune to earworms? Not on your life, Kraemer said.

"It happens to me all the time — 'Yellow Submarine' has to be one of the most recurrent themes," he said. "If you find any way to get it out of your head, I'd be very interested in hearing about it."


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