Researchers report the first objective measurement of the brain deficit in congenital amusia

While their friends enjoy the latest hit tunes, people who are tone deaf – in scientific terms, suffering from amusia – are excluded from the fun, unable to tell one note from another. The disorder can be congenital, present from birth, or acquired following injury to the brain.

In an article published online August 29, 2005, in the Annals of Neurology, researchers now report the first objective measurement of the brain deficit in congenital amusia.

The findings may have implications both for amusia and for speech learning disabilities, according to lead study author Isabelle Peretz, Ph.D., of the University of Montreal.

Peretz and collaborators at the University of Helsinki assessed brain cell responses to tones across different brain areas using electroencephalography (EEG).

Compared to control subjects, people with congenital amusia show abnormal brain activity in the right half of the brain, consistent with earlier findings by Peretz's group and others.

It may be possible to compensate for amusia by training pitch discrimination abilities. "However, it is likely that the intervention will only be effective in a 'plastic' brain, in children. We see no sign of improvement in adults," said Peretz.

Amusic adults show a normal range of intelligence and have no other brain deficits. They get little payoff from pitch training and typically find it annoying. Their performance on tests of pitch may even decrease with continued testing.

There is greater hope for children, especially since an understanding of amusia may have broader implications. Researchers believe that congenital amusia has similarities with dyslexia and related disorders.

"Our findings should contribute to understanding the origins of learning disorders – the genetic causes and their neural consequences," said Peretz.