MULTIREGIONAL ELECTRICAL ENCODING OF SOCIAL AGGRESSION Critical developments in neuroscience have included technologies for sequencing individual brain cells, progress towards completing a full mesoscale brain cell atlas in mice, new tools for monitoring and manipulating the activity of brain cells, refined imaging techniques for developing structural and functional connectome atlases in humans, and new objective measures for characterizing behavior across species. Nevertheless, a critical gap that has yet to be addressed is the development of a model that would allow this emerging catalog of cellular information to be linked to the broad functional networks that encode emotional behavior in mammals. This gap exists in part because 1) technologies that measure, monitor, and decode mesoscale activity throughout the depth of the brain during free behavior in mammalian model species have yet to be implemented in conjunction with cellular activity can be monitored and manipulated, and 2) theoretical frameworks that link cellular activity to mesoscale network activity and that generalize across subjects on a mouse-by-mouse basis have yet to be developed. Our multi-disciplinary team has built a suite of tools for studying how brain dynamics encode complex brain states. These include advanced techniques to measure and monitor brain dynamics in vivo concurrently for months across many regions located throughout the depth of the brain at high spatiotemporal resolution in freely-behaving mice, machine-learning analytic approaches that build individual circuit activity measures into composite networks, behavioral manipulations that can be used to induce brain states related to emotions, viral methods that probe the relationship between cellular changes and the expression of brain-wide neural dynamics, and closed-loop stimulation tools that can potentially test the causality of brain network-states in mediating emotion. By integrating this suite of tools in a single framework, we intend to create a model that will catalogue how the brain generates aggression. Critically, we believe that this model framework will be broadly applicable to other emotional brain states as well.