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We studied orienting and maintenance of spatial attention in audition and vision. Functional magnetic resonance imaging (fMRI) in nine healthy subjects revealed activations in the same superior and inferior parietal, and posterior prefrontal areas in the auditory and visual orienting tasks when these tasks were compared with the corresponding maintenance tasks. Attention-related activations in the thalamus and cerebellum were observed during the auditory orienting and maintenance tasks and during the visual orienting task. In addition to the supratemporal auditory cortices, auditory orienting, and maintenance produced stronger activity than the respective visual tasks in the inferior parietal and prefrontal cortices, whereas only the occipital visual cortex and the superior parietal cortex showed stronger activity during the visual tasks than during the auditory tasks. Differences between the brain networks involved in auditory and visual spatial attention could be, for example, due to different encoding of auditory and visual spatial information or differences in stimulus-driven (bottom-up triggered) and voluntary (top-down controlled) attention between the auditory and visual modalities, or both.

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We studied the effects of sound presentation rate and attention on auditory supratemporal cortex (STC) activation in 12 healthy adults using functional magnetic resonance imaging (fMRI) at 3 T. The sounds (200 ms in duration) were presented at steady rates of 0.5, 1, 1.5, 2.5, or 4 Hz while subjects either had to focus their attention to the sounds or ignore the sounds and attend to visual stimuli presented with a mean rate of 1 Hz. Consistent with previous observations, we found that both increase in stimulation rate and attention to sounds enhanced activity in STC bilaterally. Further, we observed larger attention effects with higher stimulation rates. This interaction of attention and presentation rate has not been reported previously. In conclusion, our results show both rate-dependent and attention-related modulations of STC indicating that both factors should be controlled, or at least addressed, in fMRI studies of auditory processing.

No abstract