Reorientation of Spatial Attention is Independent of the Visual Field's Meridians

A11 Reorientation of Spatial Attention is Independent of the VisualField’s MeridiansSimon R. Steinkamp1, Ralph Weidner1, Simone Vossel1,2, Gereon R. Fink1,3;1Research Centre Jülich, Germany, 2University of Cologne, Germany,3University Hospital Cologne, GermanyThe visual system can shift attention to salient or important locations in space.Changing internal settings or the appearance of salient stimuli in other placesrequires the reorientation of attention to new locations. Lesions in the rightparietal cortex may lead to an inability to orient or reorient attention to the leftvisual field. As other dimensions of the visual field are often unaffected, theorientation of attention along the horizontal meridian might be unique anddepend upon distinct neural mechanisms. In the present study, we comparedattentional reorienting along the horizontal meridian with attentional reorientingalong the vertical meridian, by using functional magnetic resonance imagingin combination with a variant of Posner’s task. Participants (n=27) performedan orientation discrimination task, where a pre-cue indicated the most likelytarget location with 80% validity. In two separate sessions, targets and cuesappeared along the horizontal or the vertical meridian. Reorienting of attentionalong the horizontal relative to the vertical meridian was compared usingvarious behavioral and functional analysis. We did not observe evidence for aspecific mechanism underlying horizontal reorienting, neither concerningbehavior, BOLD amplitudes nor effective connectivity (estimated usingdynamic causal modeling) within the relevant network of brain regions. Thiswas confirmed by a more sensitive volume of interest (VOI) approach, wherelogistic regression predicting conditions using VOI level data generalized wellacross the different directions of attentional reorienting. The data suggest thatshifts of attention along different spatial dimensions rely on the samemechanisms.Topic Area: ATTENTION: Spatia