Central pattern generators and the control of rhythmic movements

Central pattern generators are neuronal circuits that when activated can pr oduce rhythmic motor patterns such as walking, breathing, flying, and swimm ing in the absence of sensory or descending inputs that carry specific timi ng information. General principles of the organization of these circuits an d their control by higher brain centers have come from the study of smaller circuits found in invertebrates. Recent work on vertebrates highlights the importance of neuromodulatory control pathways in enabling spinal cord and brain stem circuits to generate meaningful motor patterns. Because rhythmi c motor patterns are easily quantified and studied, central pattern generat ors will provide important testing grounds for understanding the effects of numerous genetic mutations on behavior. Moreover, further understanding of the modulation of spinal cord circuitry used in rhythmic behaviors should facilitate the development of new treatments to enhance recovery after spin al cord damage.