Functional Connectivity Localizes a Distributed Supramodal Core for Naturalistic Viewing

Abstract

Understanding the brain mechanisms that support naturalistic perception is a central goal of cognitive neuroscience. Research has progressed from studying the brain with simple unimodal stimuli to employing richer paradigms that engage visual, auditory, and language modalities in naturalistic environments. Recent multimodal encoding models have shown strong promise in modeling and predicting neural responses to such complex stimuli. Previous studies, however, have primarily focused on two modalities (visual and auditory) and often highlight regions implicated in audiovisual processing (e.g., posterior STS), but do not delineate a compact, replicable subnetwork for multimodal, naturalistic stimuli. While these studies produced valuable maps of sensory integration, their scope was restricted to two modalities and they lacked replication, leaving the full picture of the multimodal integration uncertain. Moreover, no studies have localized a compact, replicable subnetwork via FC-guided ablation under naturalistic viewing. The present study advances our understanding of naturalistic perception by identifying the most informative parcels in Schaefers brain atlas that contribute to this task. Building on our earlier work demonstrating that functional connectivity can reveal parcels critical for naturalistic perception, we refine this approach by applying "top drop/bottom drop" and "top keep/bottom keep" selection strategies as well as "broken-stick" analysis to focus on regions most relevant for multimodal integration during naturalistic viewing.