RT Journal Article SR Electronic T1 Probabilistic modeling reveals coordinated social interaction states and their multisensory bases JF bioRxiv FD Cold Spring Harbor Laboratory SP 2024.08.02.606104 DO 10.1101/2024.08.02.606104 A1 Stednitz, Sarah Josephine A1 Lesak, Andrew A1 Fecker, Adeline L A1 Painter, Peregrine A1 Washbourne, Phil A1 Mazzucato, Luca A1 Scott, Ethan K YR 2024 UL http://biorxiv.org/content/early/2024/08/06/2024.08.02.606104.abstract AB Social behavior across animal species ranges from simple pairwise interactions to thousands of individuals coordinating goal-directed movements. Regardless of the scale, these interactions are governed by the interplay between multimodal sensory information and the internal state of each animal. Here, we investigate how animals use multiple sensory modalities to guide social behavior in the highly social zebrafish (Danio rerio) and uncover the complex features of pairwise interactions early in development. To identify distinct behaviors and understand how they vary over time, we developed a new hidden Markov model with constrained linear-model emissions to automatically classify states of coordinated interaction, using the movements of one animal to predict those of another. We discovered that social behaviors alternate between two interaction states within a single experimental session, distinguished by unique movements and timescales. Long-range interactions, akin to shoaling, rely on vision, while mechanosensation underlies rapid synchronized movements and parallel swimming, precursors of schooling. Altogether, we observe spontaneous interactions in pairs of fish, develop novel hidden Markov modeling to reveal two fundamental interaction modes, and identify the sensory systems involved in each. Our modeling approach to pairwise social interactions has broad applicability to a wide variety of naturalistic behaviors and species and solves the challenge of detecting transient couplings between quasi-periodic time series.HIGHLIGHTSZebrafish exhibit distinct correlated interaction states with unique timescales.Delayed interactions are visual while synchronization requires mechanosensation.A new class of hidden Markov model segments social interactions into discrete states.States alternate within a session, revealing real-time dynamics of social behavior.Competing Interest StatementThe authors have declared no competing interest.