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Kalanit Grill-Spector; Using multiple functional criteria to define high-level human visual areas in the lateral occipital and temporal lobes.. Journal of Vision 2004;4(8):90. doi: https://doi.org/10.1167/4.8.90.
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© ARVO (1962-2015); The Authors (2016-present)
Our knowledge of the human visual cortex has increased tremendously with the introduction of functional magnetic resonance imaging (fMRI). However, despite of this success, there is little consensus about the definition of areas beyond regions: V1, V2, V3 and hMT+. The debate stems from the lack of agreement on the appropriate criteria for designating a cortical region as a visual area. Physiologists have used four criteria for defining visual areas: (1) histology (2) connectivity (3) retinotopy and (4) functional selectivity. Accordingly, fMRI studies have used retinotopy and functional selectivity. However, retinotopy has been largely ignored beyond early visual cortex. Here we combined retinotopy (optimized for high-level areas) and functional tests to define high-level visual areas. Six subjects were scanned on a 3T GE scanner in block-design experiments in which we mapped: (1) Eccentricity (3, 6–12 and 12-24 degree representations) (2) Visual meridians (upper, left, lower and right) (3) Motion selectivity (low contrast moving vs. static dots) and (4) Object selectivity. By integrating data from these experiments we were able to delineate three distinct object-selective areas in the lateral aspect of the occipital and temporal lobes: (1) LO located posterior to MT: responds more strongly to objects vs. textures, contains an eccentricity map, a representation of the lower and horizontal visual meridians, and is not motion-selective. (2) An area superior to MT that responds more strongly to animals and faces (compared to objects or textures) contains a coarse eccentricity map (a central and peripheral representation) and is motion-selective. (3) An area in the STS that responds more strongly to faces (compared to animals, objects or textures) does not contain a retinotopic map and is not motion-selective. These data show that combining retinotopy with functional tests is an effective method for defining high-level visual areas.
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