CONTRIBUTION OF DIFFERENT CORTICAL AREAS IN THE TEMPORAL LOBES TO MUSIC PROCESSING

Music processing ability was studied in 65 right-handed patients who h ad undergone unilateral temporal cortectomy for the relief of intracta ble epilepsy, and 24 matched normal controls. The ability to recognize changes in note intervals and to distinguish between different rhythm s and metres was tested by presentation of sequences of simple musical phrases with variations in either pitch or temporal dimensions. The r esponses (right or wrong) enabled us to determine in which component o f the music processing mechanism the patients had deficits and hence, knowing the positions of the surgical lesions, to identify their separ ate cerebral locations. The results showed that a right temporal corte ctomy impaired the use of both contour and interval information in the discrimination of melodies and a left temporal cortectomy impaired on ly the use of interval information. Moreover, they underlined the impo rtance of the superior temporal gyrus in melody processing. The excisi on of a part of the auditory areas (posterior part of the superior tem poral gyrus) was found to be most detrimental for pitch and temporal v ariation processing. In the temporal dimension, we observed a dissocia tion between metre and rhythm and the critical involvement of the ante rior part of the superior temporal gyrus in metric processing. This st udy highlights the relevance of dissociating musical abilities into th eir most significant cognitive components in order to identify their s eparate cerebral locations.