9410934 Quinn In order to understand the molecular basis of learning, it will be necessary to (1) identify the genes which influence learning performance, (2) determine in which brain cells they are active, and (3) describe what happens when they are switched on or off. Dr. Quinn's lab has identified a mutant fly ("radish") with specific learning deficits, and will now proceed to identify the gene which produces altered learning performance in flies of this phenotype. With this information they will be able to identify the product of the radish gene and begin to determine the mechanisms by which the product acts to influence the learning process. This will have great significance for understanding both the neural and genetic factors that influence the modifiability of an organism's behavior.