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Edward Silson, Annie Chan, Adam Steel, Richard Reynolds, Dwight Kravitz, Chris Baker; A retinotopic basis for the division of category selectivity into lateral and ventral regions. Journal of Vision 2015;15(12):586. doi: https://doi.org/10.1167/15.12.586.
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High-level human visual cortex contains a repeated organization of category-selectivity on the lateral and ventral surfaces of occipitotemporal cortex. In general at least one region showing strong selectivity for each category is present on each surface. The reasons for this apparent redundancy and the mechanisms by which it is created are not well understood. Here, we argue this structure results from an extension of earlier retinotopic organization, and reflects not redundancy but distinct high-level visual representations of different locations in the visual field. Multiple independent tests were employed to measure retinotopic biases within scene-selective cortex. First, pRF mapping revealed that TOS and PPA exhibit a striking contralateral bias coupled with a pronounced upper field bias in PPA and lower field bias in TOS. Second, in an event-related experiment participants performed a demanding fixation task whilst images of scenes were presented randomly into one of the four quadrants of the visual field. Consistent with the pRF estimates, scene representations in PPA were strongest for the contralateral upper quadrant, whereas in TOS representations were strongest for the contralateral lower quadrant. Third, our behavioral experiment was based on our previous observation of a prominent open/closed distinction in the responses of PPA (Kravitz et al., 2011). Consistent with an upper field bias in PPA, we observed better behavioral performance in the upper than lower visual field when making open/closed but not manmade/natural judgments. Finally, we investigated the functional connectivity of PPA and TOS at rest. These data demonstrate that lateral and ventral scene-selective regions TOS and PPA contain functionally and behaviorally relevant biases for the contralateral lower and upper visual fields. These biases are not only consistent with anatomical projections in monkey, but are also evident in human object-selective areas, suggesting that retinotopic organization may determine the structure of category-selectivity in high-level visual cortex.
Meeting abstract presented at VSS 2015
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