Mapping inter-brain synchrony in awake, socially interacting mice using SORDINO hyperscanning

Motivation: Inter-brain synchronization enables shared understanding and coordinated behavior in social interactions, with disruptions linked to neuropsychiatric disorders. However, its underlying neuronal mechanisms remain unclear due to limitations of current imaging techniques. Goal(s): Develop a hyperscanning-fMRI platform to measure inter-brain synchronization and identify key brain hubs engaged in mouse social interactions. Approach: Using silent, motion-insensitive SORDINO-fMRI, we simultaneously imaged the brains of two interacting mice, comparing inter-brain connectivity before and after divider removal. Results: Social interaction post-divider removal elicited robust inter-brain synchronization among retrosplenial, cingulate, prelimbic, anterior insula (default mode and salience networks), and motor cortices, but not somatosensory cortex. Impact: We demonstrated a robust large-scale inter-brain synchronization in socially interacting mice using a novel, silent, motion-insensitive SORDINO-fMRI hyperscanning method, enabling future exploration of neural circuit- and network-level mechanisms behind inter-brain synchronization that are challenging to investigate with conventional approaches.