Shanshan Li^1,4 (), Sarah L Master¹, Hsin-Hung Li^1,2, Thomas C Sprague³, Ying Zhou^1,4, Kartik K Sreenivasan^4,5, Clayton E Curtis^1,6; ¹Department of Psychology, New York University, ²Department of Psychology, The Ohio State University, ³Department of Psychological and Brain Sciences, University of California, Santa Barbara, ⁴Division of Science and Mathematics, NYU Abu Dhabi, ⁵Center for Brain and Health, NYU Abu Dhabi, ⁶Center for Neural Science, New York University

How are working memory (WM) representations stored over brief delays? Neuroimaging studies consistently report persistent above-baseline activity in frontal cortex during WM maintenance but not visual cortex, while conversely, WM content can be decoded from visual cortex but less consistently in frontal cortex. Based on these findings, we hypothesized that persistent activity in frontal cortex reflects top-down feedback that enhances the fidelity of WM representations in visual cortex. To test this hypothesis, we developed a novel approach combining univariate analysis to assess trial-by-trial delay-period activation with decoding to quantify the quality of WM representations on a trial-wise basis. We applied this method to four WM datasets spanning three distinct studies, enabling a comprehensive test of our hypothesis and including testing how results generalize across tasks. Consistent with previous findings, we observed persistent activity in multiple frontal and parietal regions (but not visual cortex) during WM delays, and were able to decode memory context most robustly in V1-V3 during these same memory delays. Critically, across all datasets, trial-by-trial variations in delay activity amplitude in frontal and parietal cortices - specifically the superior precentral sulcus and intraparietal sulcus - predicted the quality of decoded WM representations in V1-V3. Thus, persistent activity in frontal and parietal cortices may reflect feedback signals targeting WM representations in visual cortex. We propose that these feedback signals may sculpt population activity in visual cortex, improving the quality memory representations.

Acknowledgements: This work was supported by the NYUAD Center for Brain and Health, funded by Tamkeen under NYUAD Research Institute grant CG012 to KKS, and R01 EY-016407 and R01 EY-033925 to C.E.C.