Crossmodal links in endogenous and exogenous spatial attention: evidence from event-related brain potential studies

The adaptive control of behaviour in response to relevant external objects and events often requires the selection of information delivered by different sensory systems, but from the same region in external space. This can be facilitated by crossmodal links in the attentional processing of information across sensory modalities. Results from recent event-related potential (ERP) studies are reviewed that investigated mechanisms underlying such crossmodal links in spatial attention between vision, audition and touch. Crossmodal attention effects were observed for early modality-specific visual, auditory, and somatosensory ERP components, indicating that crossmodal links in spatial attention affect sensory-perceptual processes within modality-specific cortical regions. ERP modulations prior to target events but sensitive to the direction of an attentional shift were remarkably similar during anticipatory covert shifts of visual, auditory, or tactile attention. These results suggest that such attentional shifts are mediated by supramodal frontoparietal control mechanisms. Finally, ERP evidence is reviewed suggesting that effects of crossmodal links in endogenous (voluntary) as well as exogenous (involuntary) spatial attention are mediated by a representations of external space which are updated across postural changes.