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Summer Sheremata, David Somers, Sarah Shomstein; Divergence and convergence in parietal activity during visual attention and short-term memory. Journal of Vision 2016;16(12):764. doi: 10.1167/16.12.764.
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© ARVO (1962-2015); The Authors (2016-present)
Visual attention and short-term memory (VSTM) are distinct yet inter-related processes. While both tasks require the selection of information across the visual field, memory also requires the maintenance of information across time and distraction. VSTM has been shown to recruit areas within the dorsal and ventral attention networks. However, because these areas have been implicated in the spatial selection, it is important to determine whether overlap of activity simply reflects attention demands common to the two tasks. Therefore, we performed fMRI studies that employed attention and VSTM tasks with identical stimuli and attentional selection demands to ask whether signal amplitude, functional connectivity, and contralateral bias reflect maintenance-specific task demands in these areas. While attention and VSTM activated similar cortical areas, BOLD amplitude and functional connectivity in the parietal cortex differentiated the two tasks. Within the dorsal attention network VSTM, increased BOLD amplitude in IPS1/2 but not FEF relative to attention. In addition, the right angular gyrus, an area of the ventral parietal cortex, showed greater deactivation compared to attention. Task demands also modulated parietal functional connectivity. Compared to the attention task, IPS1/2 was more strongly connected with other fronto-parietal areas and more weakly connected with occipital cortex. This divergence between tasks demonstrates that active maintenance in the presence of distractors is reflected in parietal activity and modulates functional connectivity with areas across the cortex. In contrast, both tasks converged on the same pattern of hemispheric asymmetry for spatial processing. A contralateral bias, defined by greater activity for items presented in the opposite hemifield, was stronger in the left than right hemisphere across tasks. Comparable spatial bias across tasks suggests that asymmetries are characteristic of selection processes in IPS. Together these results demonstrate that both parietal activity and parietal functional connectivity can distinguish between VSTM and more general attention processes.
Meeting abstract presented at VSS 2016
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