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Ghazaleh Kiani, Sherryse Corrow, Jodie Davies-Thompson, Jason Barton; The topographical representation of the human body in visual cortex. Journal of Vision 2015;15(12):752. doi: 10.1167/15.12.752.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: Motor and somatosensory cortices have orderly topographic representations of the human body, which are referred to as ‘homunculi’. Neuroimaging studies have shown regions in fusiform and occipital cortices that are activated visually by faces and others by bodies, which are adjacent to each other. Objective: We asked whether occipitotemporal regions that respond to visual presentation of parts of the human body show 1) an organized body map, and 2) a similar pattern of magnification for certain body regions. Methods: 10 subjects participated in an fMRI experiment that compared responses during viewing of short video clips of movements of 5 different body-parts (top face-half, bottom face-half, arms, torso and legs) versus their scrambled counterparts. Using a ‘winner-takes-all’ analysis for all activated voxels, we assigned each voxel a preferred body part designation. We examined the distribution of these voxels on a 2-dimensional flat map. Results: Unlike the case for motor and sensory homunculi, there was significant inter-subject variability in the spatial relationship between areas responding to different body regions, in both occipital and fusiform regions of the right hemisphere. However, the magnification patterns in both regions were similar, showing the largest representation was for the lower face, followed by the torso, upper face, arms, and legs: this pattern bore a strong resemblance to that seen in the motor and sensory cortices. Conclusion: While there are clusters that show preferential visual responses to different body parts, the topographic representation of the visual body is less organized than that for motor and sensory homunculi. Body magnification patterns were similar, though, suggesting that the relatively greater importance of the lower face and mouth region is common to motor, sensory and visual experience.
Meeting abstract presented at VSS 2015
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