Development of locomotor patterns in the absence of peripheral sense organs and muscles

The role of peripheral sense organs and muscles in specifying the circuitry of the central nervous system during ontogeny was tested in larval lobsters. Presumptive locomotor appendages, the abdominal swimmerets, were extirpated before their differentiation. Electrophysiological recordings made 2-4 weeks later from the corresponding motor nerves showed that, despite the absence of the target muscles and sense organs, normal reflexes and normal patterns of rhythmic locomotor output appeared in the swimmeret motoneurons at the usual developmental stage. Therefore, target muscles and sense organs are unnecessary to the differentiation of normal motor output patterns in this simple invertebrate locomotor system.