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Annie Chan, Sandra Truong, Chris Baker; Hand Representations in Parietal versus Temporal Cortex: Seeing You Touching Me?. Journal of Vision 2012;12(9):835. doi: 10.1167/12.9.835.
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Visual representations of body parts have been identified in both ventral and dorsal pathways. In body part selective regions in occipitotemporal cortex (Extrastriate Body Area, EBA), representations are thought to reflect the visual appearance of body parts. In parietal cortex, however, representations are primarily thought to reflect observed actions. Here, we used fMRI to investigate visual responses to the sight of body parts being touched. First, we compared responses to the sight of a static hand being brushed compared to brush alone, revealing the expected activation in EBA but also robust bilateral activation in anterior parietal cortex. We then characterized responses in both regions in three separate experiments. Experiment 1 revealed that in both regions, the sight of brushing near, but not on the hand was sufficient to elicit strong responses. Further, there was no modulation by hand laterality (left or right). However, in parietal cortex, but not EBA, viewing a static hand alone elicited weak activation, suggesting that the combined presence of an object and a hand is necessary. Experiment 2 showed little effect of perspective in either region comparing egocentric and allocentric views. Experiment 3 revealed specificity to both body part and type of action in parietal cortex but not EBA. In particular, activity in parietal cortex was reduced for seeing a foot being brushed compared to hand being brushed, and for finger movement compared to a hand being brushed. Finally, we compared selectivity for touching with selectivity for hand actions in parietal cortex (Shmuelof and Zohary, 2006) revealing adjacent but non-overlapping regions. Our results demonstrate the presence of body part representations in parietal cortex reflecting the interaction between static hands and objects, with those in EBA mainly reflecting the presence of a body part.
Meeting abstract presented at VSS 2012
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