Magnetic resonance T1-weighted images were analyzed, using voxel-based morphometry (VBM), to detect brain anatomical differences in two independent groups of adults with congenital amusia (or tone-deafness) compared to controls with normal pitch perception and no formal musical training. One sample from the Montreal Neurologic Institute included 13 amusic and 22 control individuals; a second sample from Newcastle University Medical School, UK, consisted of 8 amusics and 7 controls. On the Montreal Battery of Evaluation of Amusia (MBEA), a standardized test of music perception and memory, all amusics were severely impaired on melodic tests that discriminate changes in pitch while half had normal rhythm appreciation. A reduction in white matter concentration was detected in the right inferior frontal gyrus (IFG) of amusic subjects. White matter concentration in the right IFG was positively correlated with the melodic key-violation test and the memory tests of the MBEA, but not with rhythmic discrimination. VBM also showed more grey matter in the IFG of amusics relative to controls, corresponding to the decrease in white matter. In congenital amusics, an anomalous wiring of connections between the right IFG and the right auditory cortex is proposed, based on genetic factors and a lack of musical training and experience. Normal musical competence requires the integrity of white matter tracts in the right frontal brain. 
COMMENT. Congenital amusia is characterized by an abnormal perception of music with normal hearing and otherwise preserved cognition. An inability to sing, recognized by friends but not the subjects themselves, is associated with deficits in pitch perception, chiefly pitch direction. The prevalence of congenital amusia is estimated at 5% of the population. Familial cases are common, and the suggested mode of inheritance is autosomal dominant with incomplete penetrance. Congenital amusia is correlated with abnormal development of white matter in the right inferior frontal gyrus and its connections with the right auditory cortex. In a review of music and the brain, Stewart L et al, at Newcastle University and Institute of Neurology, London, UK , outline advances in our understanding of structural and functional organization of the brains of musicians, since the excellent publication by Critchley and Henson (1977). Different components of music (pitch, melody, rhythm, timbre and emotion) are represented by different psychological and neural mechanisms. Both congenital and acquired brain lesions in cases of disordered music appreciation are discussed. The influence of musical training on the development of auditory evoked responses and neural networks in young children has been studied using magnetoencephalography . See Ped Neur Briefs (April 1997;11:28) for further reference to the anatomy of music . The value of musical education and exposure in grade school education as an aid to academic achievement may be underestimated in some present day school curricula.