Lay Abstract PI: Friesen, Otto; and Mellon, DeForest Proposal Number: IBN-9723320 Much is known about the complex neuronal circuits that control rhythmic movements such as walking, flying in insects, and swimming in different species. A major source of neuronal complexity arises from tight coupling between neuronal oscillators that are integral components of larger brain circuits. These larger circuits then generate purposeful, coordinated movement patterns. Another source of complexity is sensory input, which can alter the activity of the oscillators. The experiments funded by this award are designed to advance the understanding of coordination and sensory modulation of neural circuits underlying movement patterns. The specific functions of sensory feedback in setting the patterns of rhythmic activity in nervous system circuits are determined. This information is then combined with the results of experiments investigating the way different circuits interact to generate larger, more complex rhythmic movements. Computer models of nervous system function are developed and tested based on the experimental data. Because of the functional unity of rhythmic movements in all animals, analytical tools developed by, and insights gained from, this research will be widely applicable to the understanding of the control of movement in all organisms, including humans, and will contribute to the base of information important for the development of artificial movement control systems.