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Grace E. Hallenbeck, Thomas C. Sprague, Masih Rahmati, Kartik K. Sreenivasan, Clayton E. Curtis; Spatial working memory representations are resistant to an intervening stimulus and behavioral task. Journal of Vision 2019;19(10):75e. doi: https://doi.org/10.1167/19.10.75e.
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© ARVO (1962-2015); The Authors (2016-present)
A robust working memory (WM) system requires the maintenance of past but relevant information in memory against a continuous flow of newly incoming but irrelevant information. Recent reports conflict on how WM representations encoded in visual and parietal cortex are susceptible to interference (e.g., Bettencourt & Xu, 2016; van Moorselaar et al, 2017; Lorenc et al., 2018; Rademaker et al, pp2018). Here, we test how WM representations are affected by an intervening task by leveraging the robust ability to decode spatial WM representations from retinotopically organized visual field maps in human cortex. We measured brain activity with high-speed fMRI (1.33 Hz) while participants performed a memory-guided saccade task. On 30% of trials the delay was blank. The remaining 70% were dual-task trials where participants performed a challenging motion discrimination task within a small aperture appearing at counterbalanced locations with respect to the WM target while remaining fixated. We used an inverted encoding model (Sprague & Serences, 2013) to reconstruct spatial WM representations across the delay interval in visual field maps defined in occipital, parietal, and frontal cortex. Performing the intervening task slightly reduced memory-guided saccade precision, indicating that the task was effective. In all visual field maps and with high fidelity, we could reconstruct the remembered location on trials with blank delays and in the epoch prior to the intervening stimulus on dual-task trials. However, the intervening task caused a temporary reduction in, but not loss of, reconstruction fidelity in all maps, accompanied by the ability to temporarily reconstruct the location of the intervening aperture. Therefore, WM may be distractor-resistant because it is supported by a widely-distributed network of brain areas.
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