Friday, August 21, 2009

The Tone Deaf and Brain circuits


People who are tone-deaf can’t detect differences in musical pitch but usually have normal hearing and speech. In the small study done in Boston, brain scans showed there was a difference in a particular brain circuit between those who were tone-deaf and those who weren’t. Among the tone-deaf, researchers discovered there were fewer connections between two areas of the brain that perceive and produce sounds.
“The anomaly suggests that tone-deafness may be a previously undetected neurological syndrome similar to other speech and language disorders, in which connections between perceptual and motor regions are impaired,” said Loui, of Beth Israel Deaconess Medical Center and Harvard Medical School.
For the study, the researchers used an MRI-based technique called diffusion tensor imaging to examine connections between the right temporal and frontal lobes.

It is known that this region, a neural “highway” called the arcuate fasciculus, is involved in linking music and language perception with vocal production.

The researchers took brain images of 20 people, half of whom had been identified as tone-deaf through listening tests. They found that the arcuate fasciculus was smaller in volume, and had a lower fibre count in the tone-deaf individuals.

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