CBB Seminar | Social Seminar ~ Roy Harpaz, Harvard University

CBB Seminar

Roy Harpaz ~ Post Doc Researcher, Department of Molecular and Cellular Biology, Engert Lab, Harvard University

Title: Algorithms of Efficient Social Information Processing in Zebrafish 

A striking example of collective behavior is fish schooling, where individuals move together in remarkable coordination. Such emergent structures offer many benefits including protection from predation, efficient foraging, and improved mating opportunities. Mechanistically, each fish must integrate cues from many neighbors to coordinate movement. How the brain manages such computations, often in highly dynamic and cluttered environments, remains largely unknown.

We investigated these processes in larval and juvenile zebrafish using naturalistic and virtual reality experiments. Zebrafish avoid computational overload by relying on simplified visual statistics, specifically the occupancy patterns of neighbors on each retina, to guide movement. They integrate and average these patterns independently in each eye and then apply a “winner-take-all” rule for binocular decisions.

Although genetically encoded, these computations are highly flexible. Social responses occur within milliseconds but adapt over minutes to hours depending on prior social density. Fish estimate density by integrating neighbor-induced looming signals over time, which suppresses responses in crowded settings and enhances them in sparse ones.

Mathematical modeling shows that these efficient computations accurately reproduce collective behaviors across development. Brain-wide imaging at cellular resolution identifies distinct neural clusters for monocular visual integration and specialized clusters in the left habenula for binocular processing. Together, these results provide a brain-wide circuit description of complex social interactions and open new directions for studying how learning, internal states, and genetics shape collective social behavior.

***Please note*** ~ All CBB | Social Seminars are meeting this year in the CGIS South S010 Tsai Auditorium due to Plaza Construction in the William James Hall.