ABNORMAL MUSHROOM BODY PLASTICITY IN THE DROSOPHILA MEMORY MUTANT AMNESIAC

IN Drosophila melanogaster, adult or larval rearing conditions influen ce brain structure. In particular, larval density affects the number o f fibers forming the mushroom bodies, a neuropil structure involved in olfactory learning. The mushroom bodies receive chemosensory inputs f rom the antennal lobes at the level of the calyx. In this study we rep ort that larval density affects calyx volume measured shortly after ec losion from the pupal case. We observe that in the memory mutant amnes iac this form of experience-dependent structural plasticity is missing , whereas it is not affected in the learning mutant rutabaga and in th e memory mutant radish. Independent of the plasticity effect, the caly ces are on average slightly bigger than wild type in amnesiac and smal ler in rutabaga flies. (C) 1998 Lippincott Williams & Wilkins.