[Brain electrical correlates of cerebral music processing in the human]

Slow brain potentials were recorded during musical tasks in 60 healthy subjects (42 right-handers and 18 left-handers). In period I the tasks (pitch comparison or distinguishing of chords) were solved and in period II the results were written down. Eye movements and vocalizations were avoided. Unilateral lateralizations of negative potentials, recorded in transversal leads between corresponding brain regions, were determined from a baseline measured in a 3s pretest period. Left-sided or right-sided lateralizations in frontal, precentral, parietal and temporal regions were taken as evidence for a stronger activation of the underlying cortical areas. During period I, music tasks caused a right-sided lateralization in 53%, a left-sided one in 39% and no lateralization in 8% of the subjects. Language and calculation tasks, however, showed greater than 80% left-sided lateralizations in the same subjects. In period II lateralizations appeared contralateral to the writing hand, mainly in pre-central leads. The subjects (N = 60) were divided into 3 groups on the basis of their musical training: 20 non-musicians, 20 amateurs and 20 professional musicians were compared. A right-sided lateralization occurred more often in non-musicians and amateurs than in professionals. Right-handers and left-handers had about equal right-sided lateralizations in musical tests. But in left-handers bilateral negativity without lateralization occurred more often and left-sided lateralization less often than in right-handers. In 20 right-handers the passive experience or enjoyment of music was investigated. While only listening to music without tasks performance 8 subjects had a right-sided lateralization, 6 a left-sided one and 6 had bilateral negativity without lateralization. We conclude that music processing, unlike language processing, is not dominant in one hemisphere. It is suggested that electrophysiological correlates of hemispheric lateralization during musical tests may depend on musical training and handedness, but statistical significance needs further investigations on more subjects.