Brains out of tune.

whose musical sense was not keen. He said: " It is odd, I can never tell 'God save the weasel' from 'Pop goes the Queen'! " T he old fellow of Sheen was in good company. Two presidents of the United States, Ulysses S. Grant (Fig. 1) and Theodore Roosevelt 1 , were tone deaf, as was Che Guevara 2. Music educators often ascribe 3 lack of musical aptitude to lack of practice. But in a paper published in Brain 4 , accompanied by a case report in Neuron 5 , Isabelle Peretz and colleagues suggest that 'congenital amusia' is a developmental disorder that can be placed alongside developmental dyslexia and specific language impairment. The possibility that people can be subject to a selective, potentially inborn deficit of music processing has been entertained for more than a hundred years. But there have been only a few anecdotal reports to support such a notion. For example, the neuro-psychologist Norman Geschwind described 6 a man from a family with several musically impaired members who was fluent in three foreign languages yet could not sing a song, discriminate the pitch of two tones, or keep a rhythm, despite having had music lessons as a child. Peretz and colleagues 4,5 set out to put these observations on firmer grounds. To rule out a general learning disorder, they selected 11 subjects from a larger group of self-declared unmusical volunteers who had achieved a high level of education, had been exposed to music during childhood lessons, and had been unsuccessful in mastering music from the start. Previous research has shown that memory for songs and different aspects of music — such as interval (the pitch difference between two tones), contour (the general direction in which a melody is moving), rhythm (the local temporal structure of a piece) and metre (its global temporal structure) — can be distinguished and are selectively impaired in patients with damage to particular parts of their brain 7. When their unmusical subjects were given a standardized battery of tests assessing these different dimensions, Peretz and co-workers found that there was a general failure in those tests involving pitch perception, whereas results in rhythm and metre tasks were more varied. In addition, the unmusical subjects were also insensitive to distortions of familiar tunes, and indifferent to dissonant chords. But they had no problem in recognizing familiar voices, environmental sounds and song lyrics. So …