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Reshanne Reeder, Michael Hanke, Stefan Pollmann; Task relevance modulates the representation of feature dimensions in the target template. Journal of Vision 2016;16(12):691. doi: https://doi.org/10.1167/16.12.691.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have found a network from prefrontal to posterior parietal and ventral visual regions involved in feature-based attention control and task-relevant content representation. There is much debate about the different functions of these regions and where stimulus information is represented in preparation for visual search. Here we investigated the representational similarity between task-relevant and task-irrelevant feature dimensions during cue encoding and target template maintenance prior to search. Subjects were cued to search for a spatial frequency, orientation, or both features of a Gabor grating and we measured BOLD signal during the cue and delay periods before the onset of a search display. Univariate analyses revealed the cue and delay periods were functionally separable, in that BOLD signal amplitude was higher in posterior brain regions during the cue period, and in prefrontal cortex during the delay period. Using representational similarity analysis, we found that regions extending from lateral occipital complex to intraparietal sulcus and frontal eye fields showed correlated activation patterns within the task-relevant feature dimension and homogeneously different activation patterns in the task-irrelevant feature dimension. Furthermore, we observed that these patterns were stronger in the delay period than in the cue period, and were particularly strong along the left anterior intra-parietal sulcus (IPS). Left anterior IPS additionally showed significant differences in the representation of single features versus conjunctions in the delay period. Together these results provide evidence for task-specific representations activated in various cortical regions from cue processing to the active search period. Left anterior IPS may play a special role in distinguishing task-relevant and task-irrelevant feature dimension information during target template maintenance prior to visual search.
Meeting abstract presented at VSS 2016
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