Finding a major key for tone deafness

Medicine & Science

July 05, 2004|By Jamie Talan | Jamie Talan,NEWSDAY

Can't keep a tune? You may get to blame your brain.

People who can't discriminate between musical tones suffer from amusia, or tone deafness, and Canadian researchers have identified a region in the brain that might be responsible.

Krista Hyde and her colleagues at the University of Montreal have been scanning the brains of 20 people who have been tone deaf since birth and have narrowed the hunt to the right auditory cortex, an area that processes pitch perception.

Amusia is no laughing matter, Hyde, a doctoral student, says. Music is such a major element of our culture, she said, that the condition "robs them of their experience of music. ... A beautiful symphony can sound like noise."

The researchers suspect that as much as 4 percent of the world's population have a congenital brain abnormality that renders them tone deaf. Others can acquire amusia after head trauma or stroke.

Of 100 people who responded to ads seeking people who can't carry a tune, Hyde said only 20 qualified for a true diagnosis of amusia - indicating many who think they're tone deaf instead simply aren't good vocalists.

Hyde's post-doctoral research was designed to figure out why people had severe problems processing music despite normal intelligence, memory and language skills. Her findings, published in the latest issue of Psychological Science, suggest that a brain abnormality impairs pitch processing.

One of her study subjects is a New York language professor whose husband was also a professor - of music. "When he wanted to take her to the symphony, she became aggressive," Hyde recalls.

Robert Zattore, a professor of neuroscience at Montreal Neurological Institute, part of McGill University in Montreal, said the human brain has evolved so that left and right sides of the auditory cortex have different structures and functions.

Studies by Zattore and others suggest that the left auditory cortex contains more white matter, suggesting that the left evolved to handle rapid-firing human speech. The right is slower but more accurate, which may explain its involvement in pitch perception.

The McGill scientist says that his work on processing music is helping unravel the mysteries of schizophrenia. Many patients with schizophrenia complain of voices that no one else can hear. Zattore and his colleagues suspect that that is a result of a disconnect between the auditory cortex and the rest of the brain.

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