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Ilja G. Sligte, H. Steven Scholte, Victor A.F. Lamme; Activation in V4 predicts fragile or durable storage in visual working memory. Journal of Vision 2008;8(6):212. doi: 10.1167/8.6.212.
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© ARVO (1962-2015); The Authors (2016-present)
Classic work on visual working memory shows that people robustly store about 4 objects for subsequent report (Luck & Vogel, 1997). Yet, when people are requested to shift attention to one item during retention by means of a retro-cue (Landman, Spekreijse & Lamme, 2003; Griffin & Nobre, 2003; Makovski & Jiang, 2007), people can report additional objects, up to 4 seconds after image off-set (Sligte, Lamme, Scholte, 2006). This suggests that some items are immediately stored in a robust form of memory, while additional items are represented in a more fragile memory store. To study the neural substrate of these different stores, we employed a similar visual working memory paradigm and concurrently measured BOLD fMRI in 8 retinotopic locations in V1 to V4. We sorted trials (correct vs. incorrect, cue during retention interval vs. match display) so that we could determine whether items at a particular retinotopic location were stored in durable (DWM) or fragile (FWM) visual working memory. We found that storage in FWM elicited selective retinotopic activation only in V4. This activation was enhanced when items were in DWM. We conclude that both storage in FWM and DWM depends on a selective and retinotopic neural representation that includes V4. Moreover, the activation level in V4 is indicative for the representational strength of the working memory representation.
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