Nonspatial intermodal selective attention is mediated by sensory brain areas: Evidence from event-related potentials

The present study focuses on the question of whether inter- and intramodal forms of attention are reflected in activation of the same or different bra in areas. ERPs were recorded while subjects were presented a random sequenc e Of Visual and auditory stimuli. They were instructed to attend to nonspat ial attributes of either auditory or visual stimuli and to detect occasiona l target stimuli within the attended channel. An occipital selection negati vity was round for intramodal attention to visual stimuli. Visual intermoda l attention was also manifested in a similar negativity. A symmetrical dipo le pair in the medial inferior occipital areas could account for the intram odal effects. Dipole pairs for the intermodal attention effect had a slight ly more posterior location compared to the dipole pair for the intramodal e ffect. Auditory intermodal attention was manifested in an early enhanced ne gativity overlapping with the N1 and P2 components, which was localized usi ng a symmetrical dipole pair in the lateral auditory cortex. The onset of t he intramodal attention eff, ect was somewhat later (around 200 ms), and wa s reflected in a frontal processing negativity. The present results indicat e that intra- and intermodal forms of attention were indeed similar for vis ual stimuli. Auditory data suggest the involvement of multiple brain areas.