Location- or feature-based targeting of peripheral attention

Using event-related fMRI we determined the differential effects of feature- versus location-based cues for directing peripheral attention. Pairs of sa me-color targets appeared on the left and on the right. A predictive cue in dicated whether the subsequent targeting of attention would be based on loc ation (left versus right) or color (red versus blue). Subjects had to press a button when the relevant pair of targets (in the cued side of space or o f the cued color) were identical in shape. The feature-based cue thus also led to a "global" expectancy of targets on either side of space whereas the location based cue elicited a more "focal" expectancy limited to one side of space. The right inferior parietal lobule was more active when attention was targeted on the basis of location than of color, There was no differen ce between left-sided or right-sided attention in this region, indicating t hat it mediated the targeting to both sides of space. These results show th at the right inferior parietal cortex plays a relatively selective role in mediating location-based and spatially focal modes of attentional deploymen t. Its relatively equal activation for leftward and rightward attentional s hifts is also consistent with models of right hemispheric dominance of spat ial attention. (C) 2001 Academic Press.