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Alan C.-N. Wong, Yetta Kwailing Wong; Level of discrimination as an organizing principle in the human ventral occipito-temporal cortex for object recognition. Journal of Vision 2014;14(10):1306. doi: https://doi.org/10.1167/14.10.1306.
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© ARVO (1962-2015); The Authors (2016-present)
Regions of the ventral occipito-temporal (vOT) cortex show preferential activations to particular object categories, such as faces, words, tools and scenes. The origin of such category-selective activations has been a topic of intense debate. A functional magnetic resonance-adaptation (fMR-A) study was conducted to investigate one candidate principle governing the organization of the vOT – level of discrimination. It is hypothesized that the medial regions of the vOT, sensitive to coarse input to the periphery of the visual field, are suited for coarse discrimination, while the lateral regions of the vOT, sensitive to foveal input with a high acuity, are suited for more specific, fine discrimination. Participants judged the color of a series of novel, artificial objects (Ziggerins) presented in (i) same-object blocks, in which the same object was presented repeatedly; (ii) different-object blocks, in which highly similar objects from the same category were presented; and (iii) different-category blocks, in which different objects across categories were presented. In general vOT activity was the lowest for same-object blocks due to adaptation, and release from adaptation for different-object and different-category blocks was found due to small and large shape changes respectively. Importantly, the medial portion of the vOT showed a larger release from adaptation for different-category than different-object blocks; towards the more lateral portion of the vOT, release from adaptation became similar for the two types of blocks. In other words, going from the medial to the lateral vOT there was a continuous change of the sensitivity bias from rough to detailed shape discrimination. Results suggest that this level-of-discrimination map can be one of the many continuous maps contributing to the seemingly discrete category-selective regions.
Meeting abstract presented at VSS 2014
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