This research will focus on the developmental plasticity and the trophic factors that are important in determining a neuron's fate in the lobster. The investigator will define the developmental and adult functions of these neurons; study the biochemical, anatomical and physiological plasticity in identifiable neurons and manipulate the "turning on and off" of transmitter using hormones. The outcome should add to our knowledge about timing of transmitter acquisition as well as assist in defining general principles guiding the biochemical differentiation of neurons.