Robert J. Zatorre
Alan C. Evans
Montreal Neurolog. Inst., McGill Univ., Montreal, PQ H3A 2B4, Canada
Cerebral blood flow changes were measured to examine the cortical basis for perceptual analysis of musical information. Twelve normal right-handed volunteers underwent positron emission tomography (PET) scanning using the bolus water technique while listening to two types of stimuli: (1) unfamiliar tonal melodies, and (2) sequences of noise bursts, acoustically matched to the melodies for duration, intensity, and onset/offset characteristics. Subtracting the latter from the former PET image provides information regarding melodic processing beyond that associated with nonspecific auditory stimulation. Anatomical localization was provided by superimposing the average PET subtraction image on the average magnetic resonance image for the subjects tested. Results indicated significant increases in blood flow while listening to melodies in the right associative auditory cortex, suggesting that specialized neural systems in the right temporal lobe participate in higher-order perceptual analysis. In addition, regions of significant activity were observed in the right occipital lobe, within areas classically described as associative visual cortex. This result may implicate these regions in hitherto unexplored aspects of auditory processings, or may possibly reflect engagement of visuospatial processing mechanisms in perception of melodies.