MUSIC
Why can some singers croon in tune while others warble off-key? The
answer's in the brain, not the ear. Researchers have identified a neural
network which seems to grant certain people perfect pitch.
Most musicians have relative pitch, or the ability to identify the
interval between two tones. But perfect or absolute pitch--the ability to
name or produce a note on demand--is rare.
Robert Zatorre, Ph.D., associate professor at the Montreal
Neurological Institute at McGill University, used positron emission
tomography (PET) to monitor the brain activity of 20 musically trained
subjects as they listened to various tones.
When asked to name the interval formed by two notes, subjects with
relative pitch used the right inferior frontal part of the cortex, which
maintains working memory. These musicians, contends Zatorre, must
consciously remember each sound in order to classify the notes'
relationship. In contrast, perfectly-tuned individuals showed no activity
in this are. suggesting that they access information already stored in
the brain.
"If you don't have perfect pitch," Zatorre explains, "you have to
hold one note in your memory till the second comes along. Then you
re-sing the interval in your head. But with perfect pitch, you
automatically know that they're, say, an F and an A, and form a major
third."
PET scans of people listening to single notes show that only those
with perfect pitch fire the left dorsolateral frontal cortex, a brain
region used in associative learning. Zatorre believes that when these
musicians hear a note, its verbal name is also retrieved. "Their
association circuitry seems to be more highly developed," he says. "They
hear a sound, it's linked to a label and the cortex lights up."
PHOTO (COLOR): Most musicians have relative pitch, or the ability
to identify the interval between two tones.
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