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Holly Lockhart, Susanne Ferber, Stephen Emrich; Neural measures accounting for flexibility in VSTM. Journal of Vision 2018;18(10):112. doi: 10.1167/18.10.112.
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Recent evidence suggests that visual short-term memory (VSTM) resources can by allocated both continuously and flexibly. However, the neural mechanisms underlying this flexibility remain unclear. Previous studies have isolated the role of the intraparietal sulcus (IPS) in the maintenance of information in VSTM; however, it is unclear whether activity in this region reflects the flexible allocation of memory resources. In the currently study, we used functional magnetic resonance imaging (fMRI) to isolate the neural substrates mediating flexible VSTM resource allocation. Participants completed a delayed-estimation task in which they were cued to remember 1, 2, or 4 items with 100% validity, or in the critical condition, participants were cued to 1 item with 50% validity. This manipulation requires flexible resource allocation across four items. This task was previously shown to reliably influence the distribution of memory resources in a flexible manner according to the cueing probability (Emrich, Lockhart, & Al-Aidroos, 2017). IPS activity showed the expected increase in activity for the memory load manipulations. In the flexible allocation condition the IPS activity demonstrated a level of activity that suggested all four objects in memory while behavioral evidence confirmed that memory resources were flexible allocated. Several regions were identified to be more active in the flexible memory allocation condition relative to a load four condition, the largest of which were the bilateral insula, cingulate gyrus, and right dorsolateral prefrontal cortex (dlPFC). Additionally, mixed linear effects modeling revealed IPS activity did not significantly predict absolute recall error; in contrast, right dlPFC activity significantly predicted absolute recall error. These results suggest that VSTM precision is in part determined by flexible resource allocation mediated by top-down attentional mechanisms.
Meeting abstract presented at VSS 2018
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