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Edward Ester, Thomas Sprague, John Serences; Visual working memory representations are distributed throughout human cortex.. Journal of Vision 2015;15(12):1115. doi: 10.1167/15.12.1115.
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© ARVO (1962-2015); The Authors (2016-present)
Visual working memory (WM) enables the representation and manipulation of fleeting visual information. Invasive neurophysiological recordings and human neuroimaging studies have revealed sustained increases in neural activity (e.g., single- and multiunit firing rates) and/or activation (e.g., the amplitude of the blood-oxygenation-level-dependent response) within a network of prefrontal, parietal, and inferotemporal cortical regions during WM storage, but it is unclear whether these responses encode memoranda or instead reflect top down signals that coordinate storage in posterior sensory areas. To examine these alternatives, we asked participants to remember and recall the precise orientation of a lateralized grating after a 10 second blank delay. Using fMRI and an orientation encoding model, we were able to reconstruct spatially global representations of a remembered – but not a forgotten – orientation within multiple subregions of retinotopically organized visual and inferior parietal cortex (e.g., Ester et al., VSS 2014). Next, we used this method to explore putative representations of the remembered orientation across regions of frontal, parietal, and temporal cortex (identified using general linear model-based localizers and/or a roving searchlight analysis). We obtained robust representations of a remembered – but not a forgotten – orientation across a distributed network of frontal and parietal cortical regions, including (but not limited to) bilateral inferior and superior parietal lobule (IPL), bilateral medial and inferior frontal gyri (IFG), bilateral cingulate cortex, and bilateral inferior temporal gyri (ITG). Moreover, trial-by-trial fluctuations in the relative “quality” of reconstructions observed in visual cortex as well as a set of left-lateralized frontoparietal and temporal ROIs (e.g., MFG, ITG) were robustly correlated with fluctuations in memory performance. These results suggest that WM representations are encoded and represented by a diffuse network of posterior sensory and anterior multimodal cortical areas.
Meeting abstract presented at VSS 2015
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