title: Rhythm generator circuits in a simple nervous system.
mesh_terms: D000818:Animals; D005724:Ganglia / Q000502:physiology; D007395:Interneurons / Q000502:physiology; D007865:Leeches; D009043:Motor Activity; D009046:Motor Neurons / Q000502:physiology; D009420:Nervous System / Q000033:anatomy & histology*; D009424:Nervous System Physiological Phenomena; D013550:Swimming