Got a song stuck in your head?
If you've ever gotten a song stuck in your head, you know how annoying
it can be. Researchers at Dartmouth University can't stop the aggravation,
but they do have a good idea what parts of the brain keep replaying the music.
Using brain imaging techniques and a good CD collection, they found
that the auditory cortex, the same part of the brain that passes
information from the ears to the brain, also holds onto musical memories.
If people are listening to familiar music, the researchers say,
they automatically call on those auditory memories to fill in gaps
when the music stops.
Using functional magnetic resonance imaging, the researchers watched
as subjects tried to mentally fill in the blanks to songs both familiar
and unfamiliar that were missing short snippets.
All participants reported hearing a continuation of the familiar, but
not the unfamiliar, tunes during the gaps. And the imaging tests showed
that gaps in the familiar songs induced more activity in the brain's
auditory association area.
"We played music in the scanner (FMRI), and then we hit a virtual
'mute' button," explained David Kraemer, a graduate student in Dartmouth's
Psychological and Brain Sciences Department and author of the study,
published in the journal Nature.
With familiar songs, "we found that people couldn't help continuing
the song in their heads, and when they did this, the auditory cortex
remained active even though the music had stopped," Kraemer added.
The researchers said the findings extend previous work on auditory
imagery and parallel work on visual memory, which both show that
sensory-specific memories are stored in the brain regions that first
experienced those events.
"It's fascinating that although the ear isn't actually hearing the
song, the brain is perceptually hearing it," said co-author William Kelley,
assistant professor of psychological and brain sciences.
The playback also differed somewhat depending on whether a song had
words. If the music gapped during an instrumental song, say the theme
from the "Pink Panther," the subjects activated different parts of the
auditory cortex, apparently going further back in the memory-processing
stream to fill in the blanks.
But when remembering songs with words, people relied only on the
more advanced structures for auditory processing.