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Stable Network Motifs with Divergent Engagement Across Memory Outcomes

Kumar A, Tyner K, Moseley R, Svalina M, Geller AS, Rutishauser U, Kramer DR, Thompson JA

2026

Abstract

Visual recognition memory depends on coordinated interactions across distributed medial temporal, prefrontal, and limbic networks, yet the sub-second large-scale network dynamics distinguishing successful from unsuccessful recognition remain poorly understood. Here we used intracranial EEG recordings from seven patients (4 female, 3 male) with medically refractory epilepsy performing a new–old visual recognition memory task to characterize time-resolved directed functional connectivity and dynamic network organization. Directed effective connectivity was estimated using bivariate Granger causality in a sliding-window framework, and dynamic community structure was identified using the Louvain modularity algorithm. Successful recognition (Hits) was associated with a qualitatively distinct network configuration: low modularity (Q = 0.05 vs. 0.09–0.15 in other conditions), a cross-hemispheric community structure integrating left medial temporal lobe (MTL) with right prefrontal cortex, and sustained network integration throughout the post-stimulus period. Right-hemisphere nodes within this cross-hemispheric community showed stronger within-community directed connectivity than left-hemisphere nodes (mean asymmetry index = 0.33, p < 0.001), consistent with right prefrontal dominance in driving network integration during successful retrieval. In contrast, Correct Rejections were characterized by early transient network segregation (onset 32 ms) dominated by right-hemisphere…

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