Our research concerns the developmental events that give rise to the mature nervous system, specifically the interplay of lineage and extrinsic influences in the formation of neural circuits. We study the adult and embryonic nervous system of the grasshopper, where many motor neurons and interneurons have been individually identified. The neurons can be classified into "families", which each arise from a single progenitor cell or neuroblast. We are using electrophysiology, intracellular staining, and immunocytochemistry to examine the diversities of neurotransmitterphenotype, of neuronal morphology, and of neuronal connectivity of lineally related neurons. Our aim is to discover the temporal and spatial sequence whereby the neurons in a lineage acquire their distinctive properties during development, and how these properties contribute to the functioning of the individual neurons in the adult nervous system.