Brain mechanisms mediating auditory attentional capture in humans.

The ability to detect and preferentially process salient auditory stimuli, even when irrelevant to a current task, is often critical for adaptive behavior. This stimulus-driven allocation of processing resources is known as "attentional capture." Here we used functional magnetic resonance imaging in humans to investigate brain activity and behavioral effects related to such auditory attentional capture. Participants searched a sequence of tones for a target tone that was shorter or longer than the nontarget tones. An irrelevant singleton feature in the tone sequence resulted in behavioral interference (attentional capture) and activation of parietal and prefrontal cortices only when the singleton was associated with a nontarget tone (nontarget singleton) and not when associated with a target tone (target singleton). In contrast, the presence (vs. absence) of a singleton feature in the sequence was associated with activation of frontal and temporal loci previously associated with auditory change detection. These results suggest that a ventral network involving superior temporal and inferior frontal cortices responds to acoustic variability, regardless of attentional significance, but a dorsal frontoparietal network responds only when a feature singleton captures attention.