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Benjamin D. Lester, Trafton Drew, Edward K. Vogel; Electrophysiological evidence of interhemispheric resource recruitment during visual working memory. Journal of Vision 2010;10(7):708. doi: 10.1167/10.7.708.
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© ARVO (1962-2015); The Authors (2016-present)
Recent neuroimaging work has shown that resources involved in the storage of information in visual working memory can be shared between cerebral hemispheres (Serences et al., in press). We examined whether similar sharing occurred during a lateralized visual working memory task using contralateral delay activity (CDA), an electrophysiological component that is sensitive to the number of items being currently held in WM. We show that ipsilateral activity increases and contralateral activity decreases during the maintenance period of the WM task, leading to a decreased CDA and suggesting that the information may be being shared. This apparent resource recruitment only occurs when no competing visual information is present: CDA amplitude did not decrease when participants had to inhibit competing information during the maintenance period. We explored the specificity of this effect by placing task irrelevant motion in attended or unattended location in space. We found evidence for resource sharing when irrelevant motion was present in unattended location, but this effect disappeared when the motion was in attended locations. In Experiment 3, we explored the time course of interhemispheric resource sharing by manipulating the onset of irrelevant motion. We found that even when the irrelevant motion onset 1500ms after the onset of the memory information, there was a rapid increase in CDA amplitude in response to the motion. This suggests that the decrease in CDA amplitude observed in the absence of competing information in related to the active maintenance of visual information rather than the initial selection or consolidation of this information.
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