The coordination of complex integrated movements is one of the most challenging tasks that faces the nervous system. An experimental approach that has proved very fruitful is the study of simple model systems. Crayfish have nervous systems where it is possible to identify a limited number of neurons that control swimming behavior. Dr. Mulloney has been a pioneer in the study of this nervous system. With NSF support he has found that the movement of each separate limb is driven by a specialized local circuit of neurons specific for that limb. Coordination of limb movements is controlled by a separate circuit of interneurons. This is a major advance in our understanding of movement control. With the renewal of this grant, Dr. Mulloney will be able to describe the synaptic organization of these local circuits and identify the properties necessary for normal coordination. He will also describe the cellular mechanisms by which inputs descending from higher centers can change the state of these local circuits to modulate swimming rate and direction. The results will have broad applications in the design of robot locomotion systems. The type of distributed control identified in this system is emerging as a general principle for the guidance of locomotion in multi-appendage systems.***//
