Research report Influence of gaze direction on crossmodal modulation of visual ERPS by endogenous tactile spatial attention

Recent evidence indicates that the spatial direction of endogenous covert spatial attention in one sensory modality can crossmodally influence early processing of stimuli in a different modality. However, spatial locations are initially coded according to different frames of reference for different modalities (e.g., body-centered for touch versus retinocentric vision) and postural changes (e.g., gaze shifts) will realign these. Here, we used event-related potentials (ERPs) to investigate how the direction of endogenous tactile attention affects sensory-specific visual ERPcomponents. Critically,bymanipulating direction ofgaze,we were ableto test whetherany crossmodal effects depend onvisual and tactile projections to a common hemisphere, on common locations in external space, or on some combination of the two. We found that both P1 and N1 visual components were modulated according to the direction of endogenous tactile attention. While the P1 crossmodal effect followed purely hemispheric constraints, the attentional modulation of N1 appeared to combine both anatomical and external spatial constraints. D 2004 Elsevier B.V. All rights reserved.