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Mengyuan Gong, Taosheng Liu; Continuous vs. categorical representation of feature-based attentional priority in human frontoparietal cortex. Journal of Vision 2017;17(10):50. doi: https://doi.org/10.1167/17.10.50.
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Previous studies suggest a functional role of dorsal frontoparietal network in representing feature-based attentional priority, yet how these features are represented remains unclear. In an fMRI experiment, we used a feature cueing paradigm to assess whether attentional priority signals vary continuously or categorically as a function of feature similarity. We presented two superimposed dot fields moving along two linear directions (left-tilted and right-tilted), while varying the angular separation between the two motion directions. Subjects were cued to attend to one of the two dot fields and respond to a possible speed-up in the cued direction. We examined how information contained in the multi-voxel neural patterns changed with the angular separation between the two directions. If attentional priority represents continuous changes of the features, priority signals in the dorsal pathway should become more similar when the angular separation between the attended directions decreases. However, if attentional priority represents attended feature in a categorical manner, then priority signals should remain largely invariant with respect to changes in the angular separation. We trained a classifier to decode the attended direction (left-tilted vs. right-tilted) for each angular separation, and found that the decoding accuracy improved with increasing angular separation in the visual cortex (V1 and V2). In contrast, decoding accuracy remained invariant to the degree of feature similarity (and significantly above chance) in the intraparietal sulcus (IPS) and frontal areas (FEF and IFJ). These results indicate dissociated roles of visual cortex and frontoparietal areas in representing attentional priority, suggesting a flexible transformation of feature-based priority from continuous to categorical representation along the dorsal visual streams.
Meeting abstract presented at VSS 2017
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