PET was used to test the hypothesis that similar neural systems are involved in attending to spectral and to spatial features of sounds. In each of four conditions subjects heard tones varying randomly in frequency and location and responded to either the low- or the high-frequency stimuli, ignoring location, or to stimuli on the left or right, ignoring frequency. In comparison to a silent baseline, CBF increases were observed in auditory cortex bilaterally and in the right superior parietal, right dorsolateral frontal, and right premotor regions, with no modulation as a function of attentional condition. Analysis of regional covariation indicated a coordinated CBF response between the right parietal region and the right frontal and middle temporal regions. The data imply that auditory attention engages a network of right-hemisphere cortical regions for both spatial location and tonal frequency and support a model whereby auditory attention operates at a level at which separate features have been integrated into a unitary representation.
Copyright 1999 Academic Press.