September 2017
Volume 17, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2017
Effect of Task on Object Category Representations Across Human Ventral, Dorsal, and Frontal Brain Regions
Author Affiliations
  • JohnMark Taylor
    Department of Psychology, Harvard University
  • Maryam Vaziri-Pashkam
    Department of Psychology, Harvard University
  • Yaoda Xu
    Department of Psychology, Harvard University
Journal of Vision August 2017, Vol.17, 287. doi:10.1167/17.10.287
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      JohnMark Taylor, Maryam Vaziri-Pashkam, Yaoda Xu; Effect of Task on Object Category Representations Across Human Ventral, Dorsal, and Frontal Brain Regions. Journal of Vision 2017;17(10):287. doi: 10.1167/17.10.287.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Recent evidence demonstrates that dorsal visual stream regions represent not just "where" or "how" information, but also object identity ("what") information like the ventral stream. Here, we further explored the hypothesis that the dorsal stream encodes object representations in a manner that also reflects task demands, whereas the ventral stream encodes objects in a relatively task-invariant manner. We also examined responses in a frontal ROI corresponding to the frontal eye field (FEF), as it belongs to the dorsal attention network along with the intraparietal sulcus (IPS), and since frontal regions also participate in object categorization tasks. In our fMRI MVPA study, participants viewed blocks of pictures from 8 object categories and did either a category oddball task (e.g., respond to a face in a block of houses) or a one-back task (e.g., respond to the same face appearing twice in a row). The oddball task thus drew participants' explicit attention to object category while the one-back task drew attention to the exact exemplar shown. We examined object category representations across a number of ROIs, including object responsive regions in lateral occipital cortex, inferior and superior IPS, and FEF. Consistent with past research, we obtained significant object category decoding across both visual pathways, and additionally in FEF. Category decoding was not enhanced by the category oddball task, suggesting that information extracted in the one-back task was sufficient to distinguish categories. We found that task and category contributed roughly equally to the category representational structures in the dorsal and frontal ROIs, but in ventral regions category contributed much more than task to the category representational structures. Task context thus plays a more prominent role in shaping object category representation in dorsal and frontal regions than in ventral regions. Supported by NIH grant 1R01EY022355 to YX

Meeting abstract presented at VSS 2017

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