Attentional modulation of multisensory integration across the cortical hierarchy.

In a multisensory environment, attention prioritizes behaviorally relevant sensory inputs not through a single mechanism but by modulating neural activity across the cortical hierarchy. Yet most studies focus on attentional modulation of unisensory processing and do not specify how attention resolves competition between the senses, or how its effects differ across cortical levels with distinct functional roles. Here, we review human, non-human primate, and rodent studies to argue that attention modulates multisensory processing at three levels. In sensory cortices, it adjusts local response gain and the temporal phase of incoming signals. In association cortices, it shapes the integration of converging inputs, enhancing the attended modality while suppressing competing ones. In the prefrontal cortex, it selects the relevant modality, monitors cross-modal conflict, and resolves the resulting perceptual uncertainty. Critically, these levels do not operate independently. Attention-dependent changes in inter-areal connectivity coordinate modulation across the hierarchy. This review suggests that attentional control of multisensory perception is best understood as a distributed division of labor that extends the priority-map framework of attentional selection to multisensory conditions, in which each cortical level contributes to constructing and updating a unified priority representation of the sensory environment. Attention is therefore an inherently integration-sensitive process, shaped by whether cross-modal signals are integrable, rather than a uniform amplification of sensory signals.