Research interest concerns the cellular mechanisms regulating functional and developmental plasticity in the nervous system. Synaptic terminals and growth cones in Drosophila mutants deficient in learning ability are analyzed by a combination of electrophysiological, anatomical, and genetic techniques. These learning mutants are defective in specific steps of second messenger systems and cause abnormal synaptic function, and growth cone motility, and neurite growth. Another class of mutations that affect ion channels are used to study the influence of neuronal activity on behavioral and developmental plasticity. Double-mutant combinations allow us to determine how channel activity and second messenger systems interact to regulate neuronal growth and synaptic function required in learning and memory processes. Genetic mosaics mosaicism and targeted expression of transgenes can be constructed used to analyze the behavioral and physiological consequences of introducing mutant neurons to alter different parts of the neural circuits involved in specific behavioral tasks.