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Akiko Ikkai, Balaji Lakshmanan, Susan Courtney; Disengagement of Sensory Regions During the Maintenance of Abstract Information in Working Memory. Journal of Vision 2013;13(9):4. doi: 10.1167/13.9.4.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have shown that concrete and abstract information may be maintained in working memory (WM) via activity of different regions in the parietal and the prefrontal cortices. However, mechanisms by which concrete and abstract information are maintained in WM are still unclear. Here, we used electroencephalogram (EEG) to test the hypothesis that abstract information is represented in WM as an active pattern of neural activity that is similar to, but independent from, the activity that represents concrete information in WM. Subjects performed two types of WM task; one required the maintenance of locations of items ("item-specific"), which involved memory for a particular retinotopic location, while the other required maintenance of the relative location of items (e.g. left of, right of, "relation"), which was not associated with a specific location. Consistent with previous results, we found that alpha power in posterior electrodes was greater for electrodes ipsilateral to the cued visual field than contralateral. In addition, we found that this laterality effect was stronger in the item-specific than in the relation condition. Multivariate pattern classification revealed that, during the delay period, the degree to which the posterior electrodes represented the cued visual field was significantly lower in the relation than in the item-specific condition. Direct comparison between conditions revealed that alpha power in posterior electrodes was greater bilaterally in relation than item trials, indicating that sensory regions were suppressed during the maintenance of abstract information. Taken together, the results suggest item-specific, sensory-related, information may be maintained via suppression of regions that represent irrelevant sensory information. On the other hand, relational, or abstract, information appears to rely on disengagement of sensory regions, suggesting that abstract information is maintained in an active form involving different mechanisms than the maintenance of concrete information.
Meeting abstract presented at VSS 2013
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