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Lior Bugatus, Kevin Weiner, Kalanit Grill-Spector; Differential representation of category and task information across high level visual cortex and ventro-lateral prefrontal cortex. Journal of Vision 2016;16(12):256. doi: 10.1167/16.12.256.
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The human brain contains functional networks across lateral occipital (LOTC), ventral temporal (VTC), and ventro-lateral prefrontal (VLPFC) cortices that are involved in processing visual categories. However, it is unknown how the combination of cognitive task and visual category affects the neural responses of regions within these networks. Here we addressed this question by scanning 12 subjects using fMRI while they viewed stimuli from five categories: faces, bodies, houses, cars, and pseudo-words. While viewing these categories, subjects performed one of three tasks in separate runs across the same session, with task order counterbalanced across subjects: Oddball: subjects detected a randomly presented phase-scrambled image. Working memory: subjects indicated whether a stimulus repeated after an intervening image. Selective attention: subjects viewed superimposed images from two categories, attended to one stimulus category, and reported when the attended stimulus was flipped upside-down. Using a data-driven approach, we examined distributed neural responses in anatomically defined regions of interest for each subject (Fig. 1A). We generated representational similarity matrices containing pairwise correlations between distributed responses across runs for each combination of task and visual category (Fig. 1B). Results show that distributed responses in LOTC and VTC are highly similar for the same visual category across tasks (F(2,132) = 41.47, p < 0.001). In contrast, distributed responses in VLPFC were similar for the same cognitive task across different visual categories (F(2,132) = 6.44, p = 0.002; Fig. 1C). Across subjects, a regression model (R2 > 0.45 for all subjects and ROIs) showed that the category effect was twice as large as the task effect in LOTC and VTC (βcategory=0.332+/-0.029, βtask=0.17+/-0.017), whereas in VLPFC the task effect was five times larger than the category effect (βcategory=0.057+/-0.009, βtask=0.281+/-0.04). Taken together, our data reveal a differential representation of category and task information across high-level visual cortex and VLPFC.
Meeting abstract presented at VSS 2016
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