Learning and memory is not limited to complex brains of higher organisms. Even simple animals like Drosophila larvae are able to evaluate odors based on previous experience, which can either be positive, i.e. rewarding (sugar, moderate heat) or negative, punishing (electric shock, high salt concentration). Yet, how perception and processing of sensory information affects behavioral decisions is not well understood in any organism. Therefore the Drosophila larva, which includes no more than 3,000 functional neurons and still displays a considerable behavioral repertoire, serves as a particularly suited model for studying the basis of learning and memory. A comparative analysis of olfactory learning reinforced by gustatory, temperature and electric stimuli will therefore help to identify the general but also the specific requirements of neuronal plasticity from the cellular and molecular up to the behavioral level.
