Ontogeny of rhythmic motor networks in the stomatogastric nervous system

We used the lobster Homarus gammarus to study the ontogeny of neural networ ks involved in rhythmic behaviours. Since in the adult the neural networks belonging to the stomatogastric nervous system and controlling the rhythmic movements of the foregut are well characterised, we have studied them duri ng ontogeny. While this foregut develops slowly throughout embryonic and la rval stages, the neuronal population of these motor networks is quantitativ ely established since the mid-embryonic period. Moreover, in the embryo, th is neural population is organised into a single functional network that dis plays a unique motor output. By contrast, in the adult the same neuronal el ements are organised into three neural networks that express independent mo tor programs. Our results indicate that the multiple adult networks are par titioned progressively from a single embryonic network during development.