POPULATION BEHAVIOR AND SELF-ORGANIZATION IN THE GENESIS OF SPONTANEOUS RHYTHMIC ACTIVITY BY DEVELOPING SPINAL NETWORKS

During development spinal networks generate recurring episodes of rhyt hmic bursting that can be recorded from motoneurons and interneurons. Optical imaging has identified a set of propriospinal interneurons tha t may be important in the production of this activity. These neurons a re rhythmically active, are recurrently interconnected and have powerf ul projections to motoneurons. The excitability of this propriospinal network is depressed by activity and recovers in the interval between episodes. These and other observations have been formulated into a qua litative model in which population behavior and self-organization are responsible for the spontaneous activity generated by developing spina l networks.