AUDITORY SELECTIVE ATTENTION - AN FMRI INVESTIGATION

In the present experiment, 25 adult subjects discriminated speech toke ns ([ba]/[da]) or made pitch judgments on tone stimuli (rising/falling ) under both binaural and dichotic listening conditions. We observed t hat when listeners performed tasks under the dichotic conditions, duri ng which greater demands are made on auditory selective attention, act ivation within the posterior (parietal) attention system and at primar y processing sites in the superior temporal and inferior frontal regio ns was increased. The cingulate gyrus within the anterior attention sy stem was not influenced by this manipulation, Hemispheric differences between speech and nonspeech tasks were also observed, both at Broca's Area within the inferior frontal gyrus and in the middle temporal gyr us. (C) 1996 Academic Press, Inc.