Poster A9, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Region-specific neural consequences of Biased-Competitional Heterogeneity of the Effects of Attentional Prioritization
Andrew D Sheldon1, Elyana Saad1, Bradley R Postle1; 1University of Wisconsin, Madison
A recent study applying multivariate analysis to whole-brain fMRI showed that attention to a single stimulus increased the strength of its representation in many regions, including occipital, intraparietal sulcus, and precentral sulcus (Ester et al., 2016). This was interpreted as blurring the distinction between “sources” and “sites” of attention. Here, we used a visual search task to study the effects of attention on the neural representation of two simultaneously presented items, one in each visual hemifield. After the brief presentation of a search target (face, doughnut, or abacus), then a delay, the search array comprised the target and a distractor, both flickering at 1 Hz and unpredictably changing state. Upon array offset, subjects reported the number of state changes the target had undergone. Next, the array reappeared, with the items in the same location and a cue indicating (with p = .5) which of the two was the target. Multivariate pattern analysis in occipital cortex revealed that the effects of attention differed in the two hemispheres: contralateral to the target, target representation was boosted and distractor suppressed to baseline levels; ipsilateral to the target, both stimuli were represented above baseline, but at a level lower than the contralateral target. In frontal and parietal cortex, in contrast, no laterality was observed, and only the target was represented above baseline levels. Thus, attention biases the competition for representation in occipital cortex, whereas frontal and parietal activity is consistent with the representation of a search template.
Topic Area: ATTENTION: Nonspatial