FUNCTIONAL-ANATOMY OF HUMAN AUDITORY ATTENTION STUDIED WITH PET

Positron emission tomography was used to investigate the functional an atomy of selective auditory attention in 17 right-handed male voluntee rs who submitted to different tasks: silent rest (REST), listening to frequent low- or rare high-pitched tones (LIS) delivered randomly to t he right or the left ear, selective auditory attention where subjects had to attend to deviants in one ear, right (ATTR) or left (ATTL). Six subjects had the series REST, LIS, ATTR twice, eight subjects the ser ies REST, LIS, ATTL, and the last three subjects the series REST, ATTR , ATTL. Event-related potentials were simultaneously recorded with PET and showed significant task and electrode site effects on the N100 am plitude, When compared to REST, LIS elicited bilateral temporal activa tions of the Heschl's gyri and the planum temporale, with a significan t rightward asymmetry, and of the posterior part of the superior tempo ral gyrus. Significant right precentral and anterior cingulate gyri no rmalized regional cerebral blood flow increases were observed in the f rontal lobe, Both the ATTR and the ATTL conditions, compared to LIS, a ctivated the supplementary motor area, bilateral precentral, and left postcentral cortices without any temporal cortex activation. In additi on, the ATTL condition resulted in a right prefrontal cortex activatio n. Pooling the 14 subjects revealed an asymmetry in the superior tempo ral gyrus favoring the cortex contralateral to the attended ear, Two m ajor networks seem thus to be involved during selective auditory atten tion: (1) a local temporal network, on which selective attention produ ces a modulation of the functional lateralization, and (2) a frontal n etwork that could mediate the temporal cortex modulation by attention. (C) 1997 Academic Press.