Dissociable Neural Correlates of Multisensory Coherence and Selective Attention.

Previous work has demonstrated that performance in an auditory selective attention task can be enhanced or impaired, depending on whether a task-irrelevant visual stimulus is temporally coherent with a target auditory stream or with a competing distractor. However, it remains unclear how audiovisual (AV) temporal coherence and auditory selective attention interact at the neurophysiological level. Here, we measured neural activity using EEG while human participants (men and women) performed an auditory selective attention task, detecting deviants in a target audio stream. The amplitude envelope of the two competing auditory streams changed independently, while the radius of a visual disk was manipulated to control the AV coherence. Analysis of the neural responses to the sound envelope demonstrated that auditory responses were enhanced largely independently of the attentional condition: both target and masker stream responses were enhanced when temporally coherent with the visual stimulus. In contrast, attention enhanced the event-related response evoked by the tran)sient deviants, largely independently of AV coherence. These results provide evidence for dissociable neural signatures of bot)tom-up (coherence) and top-down (attention) effects in AV object formation. [ABSTRACT FROM AUTHOR]